f\ 


LfGRA.RY 

UNIVERSITY  OF 
CALIFORNIA 

I     SAN  DIEGO 


34-1 

LU^ 

XX 


ON  CERTAIN  ELECTRICAL  PROCESSES  IN  THE 

HUMAN  BODY  AND  THEIR  RELATION  TO 

EMOTIONAL  REACTIONS 


BY 

FREDERIC  LYMAN  WELLS 

AND 

ALEXANDER  FORBES 


ARCHIVES    OF    PSYCHOLOGY 


KDITED    BY 

t.  S.  WOODWORTH 


No.  16,  MARCH,  1911 


FROM  THE  PSYCHOLOGICAL,  LABORATORY  OF  THE  McLEAN 
HOSPITAL,  WAVKRLEY,  MASS. 


CONTENTS 

PAGE 

I.    PHYSICAL  AND  PHYSIOLOGICAL   1 

II.    SOUBCES  OF  EBBOB  IN  PRACTICAL  APPLICATIONS  21 

III.  ON  THE  REACTION  DEFLECTION  AS  RELATED  TO  THE  INTENSITY  OP 
EMOTIONAL  RESPONSE,  WITH  SPECIAL  BEFEBENCE  TO  THE  ASSO- 
CIATION EXPEBIMENT  26 

APPENDIX  :   EXAMINATION  OF  PATIENTS    37 

LlTEBATUBE    . .  39 


ON  CERTAIN  ELECTRICAL  PROCESSES  IN  THE  HUMAN 

BODY  AND  THEIR  RELATION  TO  EMOTIONAL 

REACTIONS 


I.     PHYSICAL   AND   PHYSIOLOGICAL 

THIS  report1  deals  with  experiments  conducted  to  develop  the 
best  available  method  of  applying  the  so-called  "psycho-galvanic 
reflex"  to  the  study  of  the  emotional  reactions  both  in  normal 
individuals  and  various  forms  of  psychoses.  The  work  is  divided 
into  three  parts,  as  follows:  (1)  the  investigation  of  the  physiolog- 
ical causes  of  the  galvanometric  deflections;  (2)  the  study  of  sources 
of  error  in  their  use  arising  from  physical  causes,  and  of  the  methods 
of  eliminating  them;  (3)  the  testing  of  the  value  of  the  deflections 
as  indicators  of  emotion  by  statistical  comparison  with  the  intro- 
spective estimates;  and  supplementarily,  the  application  of  the 
method  of  inquiry  to  the  study  of  nervous  and  mental  disorders. 

Most  of  the  time  at  our  disposal  was  devoted  to  the  first  three 
portions  of  the  problem,  and  the  few  experiments  with  patients  were 
carried  on  rather  with  a  view  to  testing  the  methods  of  application 
than  with  the  hope  of  securing  any  notable  psychological  informa- 
tion. 

The  apparatus  at  the  beginning  of  the  experiments  consisted  of 
(a)  a  Leeds  and  Northrup,  Type  H,  D'Arsonval  galvanometer,  sen- 
sitivity 38  X  10"10  amperes,  (6)  the  Ayrton  shunt,  (c)  non-polar- 
izable  electrodes  of  the  calomel  type,  (d)  the  Gordon  cell,  where  an 
outside  current  is  used.  The  deflections  are  read  direct  from  a  milli- 
meter scale,  2  m.  distant  from  the  galvanometer  mirror.2  The  elec- 

1  The  material  here  presented  was  collected  almost  entirely  during  the  time 
between  October  1  and  December   1,   1909.     For  this  reason  the  observations 
consist  largely  of  single  experiments,  which  seem  to  the  writers,  however,  to 
reflect  with  comparative  accuracy  the  properties  of  the  method  under  consid- 
eration.    In  view  of  present  conditions  in  the  problem,  their  publication  seems 
justified;  cf.  Dunlap,  Psych.  Bull,  VII.,  174-177,  also  Sidis'  reply,  Psych.  Bull., 
VII.,  321-322.    The  second  named  writer  is  mainly  responsible  for  the  work  up 
to  p.  26  and  from  this  point  the  first  named. 

2  Values  are  uniformly  given  in  terms  of  mm.  deflections.     With  the  gal- 
vanometer  at   full   sensibility,   the   current   is    19  X  10~10   ampfere   per   mm.   of 
deflection;   when  cell-current  is  used,  the  current  is   1900  X  10~10  ampere  per 
mm.  of  deflection  unless  otherwise  specified. 

1 


2  ELECTRICAL  PROCESSES  IN  THE  HUMAN  BODY 

trodes  were  constructed  of  glass  tubes  shaped  like  ordinary  test  tubes, 

3  cm.  inside  diameter,  15  cm.  long,  with  the  conducting  wires  sealed 
in  the  bottom  point  of  each.    These  were  fitted  into  holes  in  a  pair 
of  horizontal  boards  on  each  side  of  a  massage  table.     The  subject 
reclined  on  this  table  with  the  hands  strapped  to  the  boards,  palms 
down,  with  the  middle  finger  protruding  downward  in  the  holes, 
each  being  immersed  in  the  fluid  to  a  depth  of  between  4  and  5  cm. 
The  straps  were  drawn  tight  enough  to  limit  the  motions  of  the  hands 
to  a  small  range.    Moreover,  the  position  was  comfortable  and  there 
was  no  tendency  to  move  the  hands  during  the  experiments.     The 
depth  of  immersion,  therefore,  remained  practically  constant  and 
with  it  such  changes  of  resistance  as  would  be  caused  by  a  change  in 
the  area  of  the  surface  immersed  or  by  a  change  in  the  length  or 
shape  of  the  conducting  column  of  fluid.     In  some  of  the  first  ex- 
periments,   funnels   with    saturated    cotton    were    inserted   in    the 
tubes ;  the  hands  were  strapped  down  with  the  palms  in  contact  with 
the  cotton.    Evaporation  caused  such  changes  in  resistance  that  this 
method  was  soon  abandoned  for  that  of  immersing  the  fingers.    With 
the  subject  and  apparatus  thus  arranged,  a  large  number  of  experi- 
ments were  carried  on  in  which  the  subject  responded  in  the  usual 
manner  to  a  series  of  association  words  and  after  a  short  interval 
graded  the  feeling  aroused  as  (A)  strongly  emotional,   (B)  rather 
emotional,  (C)  rather  unemotional,  (F)  practically  devoid  of  emo- 
tional reaction.     With  this  form  of  experiment  as  the  basis  of  our 
method,  a  variety  of  studies  were  carried  on  to  learn  the  sources  of 
error  psychical  and  physical  in  its  use,  and  to  modify  the  procedure 
and  apparatus  accordingly. 

Before  describing  the  experiments,  it  may  be  well  to  mention 
some  of  the  disadvantages  in  other  forms  of  apparatus  which  led  to 
the  adoption  of  that  which  is  described  above.  Dry  metal  plates, 
which  have  been  used  in  many  experiments,  have  the  serious  ob- 
jection that  changes  in  pressure  or  in  area  of  the  surface  in  contact 
produce  marked  changes  in  the  deflections,  thereby  confusing  the 
picture.  The  use  of  copper  plates  in  a  strong  electrolyte  has  the  dis- 
advantage of  introducing  an  electromotive  force  greater  than  that 
produced  by  the  body.  The  result  of  this  is  that  in  studying  the 
causation  of  deflections,  one  is  handicapped  in  the  effort  to  dis- 
criminate between  changes  in  body  resistance  and  changes  in  electro- 
motive difference  of  potential  developed  by  the  body.  Calomel 
electrodes  are  relatively  non-polarizable  and  with  them  it  is  often  pos- 
sible to  conduct  an  experiment  without  the  development  of  a  differ- 
ence of  potential  between  the  two  electrodes  greater  than  .0001  volt, 
while  the  difference  of  potential  between  the  two  hands  varies  from 


PHYSICAL   AXD   PHYSIOLOGICAL  3 

0  to  .006  volt.  These  values  are  easily  calculated  by  measuring  the 
resistance  of  the  body  with  a  current  of  known  voltage  and  by 
proper  interpretation  of  other  observations  noted  below. 

There  has  been  much  discussion  about  the  nature  of  the  physio- 
logical processes  involved  in  the  psycho-galvanic  reflex.  Physically, 
the  chief  point  under  discussion  is  whether  the  galvanometric  de- 
flections are  caused  by  changes  in  electrical  difference  of  potential  or 
in  body  resistance.  Physiologically,  the  question  is  of  what  organs 
are  the  seat  of  the  phenomena.  Peterson  and  Jung  discuss  these  ques- 
tions as  follows  :3 

' '  So  far  as  has  yet  been  determined,  it  would  seem  that  the  sweat 
glandular  system  is  the  chief  factor  in  the  production  of  this  electric 
phenomenon,  inducing  on  the  one  hand  under  the  influence  of  nervous 
irritation  a  measurable  current  or,  on  the  other  hand,  altering  the 
conductivity  of  the  body.  Since  water  contact  excludes  changes  in- 
duced by  pressure  on  metal  electrodes,  and  blanching  of  the  fingers 
by  the  Esmarch  bandage  excludes  changes  in  connection  with  the 
blood  supply,  both  of  these  factors  play  but  a  small  part  in  the  devia- 
tions of  the  galvanometer.  Change  in  resistance  is  brought  about 
either  by  saturation  of  the  epidermis  with  sweat,  or  by  simple  filling 
of  the  sweat-gland  canals  or  perhaps  also  by  intracellular  stimula- 
tion ;  or  all  of  these  factors  may  be  associated.  The  path  for  the  cen- 
trifugal stimulation  in  the  sweat-gland  system  would  seem  to  lie  in 
the  sympathetic  nervous  system.  These  conclusions  are  based  upon 
facts  at  present  at  hand  and  are  by  no  means  felt  to  be  conclusive. ' ' 

Sidis  and  Kalmus  claim  to  have  proved  that  the  deflections  are 
caused  by  changes  in  potential  developed  within  the  body  and  to  have 
excluded  resistance  changes  and  sweat-gland  activity  from  playing 
any  part. 

The  various  possible  physiological  explanations  may  be  enume- 
rated as  follows:  Changes  of  electrical  potential  may  be  caused  by 
"action  currents"  emanating  from  voluntary  muscles,  from  the 
smooth  muscles  of  the  blood  vessels,  from  nerve  trunks,  or  from 
sweat-glands.  They  might  also  be  caused  by  electro-chemical  action 
between  the  sweat  and  the  electrolyte  in  the  electrodes.  They  might 
be  caused  by  thermo-electric  phenomena  at  surfaces  of  contact  be- 
tween electrically  different  substances  within  the  tissues  or  at  the 
point  of  contact  between  the  tissues  and  the  electrolyte.  Resistance 
changes  might  be  caused  by  vaso-dilation  or  vaso-constriction  or 
by  sweat-gland  activity.  In  the  latter  case,  they  might  result  from 
change  in  the  glandular  tissue  or  from  filling  and  distention  of  the 
sweat  tubules. 

•  Brain,  XXX.,  p.  158. 


4  ELECTRICAL   PROCESSES   IN   THE   HUMAN   BODY 

The  assertion  by  Sidis  and  Kalmus  that  resistance  changes  have 
been  excluded  is  based  on  the  following  experiments  and  reasoning. 
"Hypodermic  needles  were  inserted  well  under  the  skin  until  blood 
flowed  freely.  The  hands,  with  the  needles  in  position,  were  placed 
within  the  liquid  electrodes."  After  establishing  this  connection 
between  the  body  fluids  and  the  electrolyte,  and  thus  eliminating 
skin  resistance,  deflections  were  obtained  similar  to  those  without 
needles.  This  is  said  to  prove  that  changes  in  skin  resistance  do  not 
cause  the  deflections.  Body  (subcutaneous)  resistance  within  the 
skin  is  said  to.  be  ruled  out  as  follows :  ' '  Heating  and  cooling  the 
arms  put  in  an  Esmarch  bandage  so  as  to  exclude  circulatory  varia- 
tions brought  about  galvanometric  deflections.  The  experiments 
with  hot  and  cold  applications  gave  but  slight  variations,  insuffi- 
cient to  account  for  the  galvanometric  phenomena  observed  under 
the  influence  of  emotional  states.  The  variations  due  to  raising  the 
temperature  did  not  differ  from  those  due  to  lowering  the  tempera- 
ture. Furthermore,  after  a  minute  or  two  of  continuous  cooling  or 
heating  the  arms,  the  reading  was  the  same  as  that  before  the  tem- 
perature changed.  The  hot  and  cold  applications  acted,  therefore, 
in  the  nature  of  mere  temperature  stimulations."  From  this  it  is 
argued  that  the  deflections  are  not  traceable  to  resistance  changes 
resulting  from  heating  of  the  body.  Esmarch  bandages  were  used 
to  exclude  circulatory  changes  and  deflections  still  followed  the  use 
of  stimuli.  The  conclusions  are  summed  up  as  follows:  "Our  ex- 
periments go  to  prove  that  the  causation  of  the  galvanometric  phe- 
nomena can  not  be  referred  to  skin  resistance,  nor  can  it  be  referred 
to  variations  in  temperature,  nor  to  circulatory  changes  with  possible 
changes  in  the  concentration  of  the  body-fluids.  Since  the  electrical 
resistance  of  a  given  body  depends  on  two  factors — temperature  and 
concentration — the  elimination  of  both  factors  in  the  present  case 
excludes  body  resistance  as  the  cause  of  the  deflections.  Our  experi- 
ments, therefore,  prove  unmistakably  that  the  galvanic  phenomena 
due  to  mental  and  physiological  processes  can  not  be  referred  to 
variations  in  resistance,  whether  of  skin  or  body.  Resistance  being 
excluded,  the  galvanometric  deflections  can  only  be  due  to  varia- 
tions in  electro-motive  force  of  the  body." 

The  evidence  does  not  seem  to  be  conclusive.  The  fact  that  when 
skin  resistance  is  eliminated  by  the  use  of  needles  deflections  still 
occur,  shows  that  under  those  conditions  change  in  skin  resistance  is 
not  the  sole  cause  of  deflections,  but  it  does  not  exclude  it  as  a  con- 
tributing cause,  nor  under  other  conditions,  as  the  main  cause. 
The  conclusion  that  heating  and  cooling  the  arms  merely  acted  as 
thermal  stimuli  is  doubtless  correct,  but  it  does  not  follow  that  the 


PHYSICAL   AND   PHYSIOLOGICAL  5 

deflections  are  independent  of  thermal  changes  in  the  body;  for 
owing  to  the  great  insulating  power  of  the  subcutaneous  fat  and  the 
rapid  circulation  of  the  blood,  it  is  doubtful  if  the  body  fluids 
were  perceptibly  heated  or  cooled  in  this  experiment. 

In  the  present  experiments,  the  relative  influence  of  potential 
and  resistance  changes  in  causing  deflections  was  studied  by  use  of 
two  separate  methods.  One  was  to  connect  the  galvanometer  with 
electrodes  as  nearly  isopotential  as  possible  and  insert  the  fingers  in 
these.  The  other  was  to  connect  the  body  and  galvanometer  in 
series  with  a  Gordon  cell  of  known  voltage.  For  the  first  method, 
the  various  electrode  tubes  which  had  been  prepared  were  connected 
with  the  galvanometer  in  pairs  to  show  their  relative  potentials. 
This  was  done  as  follows :  the  wires  leading  from  the  two  electrodes 
to  be  tested  were  connected  with  the  two  poles  of  the  galvanometer. 
The  ray  of  light  from  the  galvanometer  mirror  was  brought  to  the 
zero  point  in  the  middle  of  the  scale,  before  the  circuit  was  closed. 
Two  limbs  of  a  Y-shaped  tube  were  then  introduced  into  the  two 
tubes  and  the  electrolyte  sucked  up  far  enough  to  establish  a  fluid 
connection  between  the  electrodes.  With  all  but  one  of  the  pairs 
thus  tried,  the  galvanometric  deflection  was  over  400  mm.  With 
the  remaining  pair  (nos.  2  and  3)  the  deflection  was  -f-  50  mm.  at 
the  beginning  of  the  experiment,  and  after  testing  each  with  each 
of  the  other  tubes,  it  was  —  92  mm.,  the  change  being  probably  the 
result  of  polarization.  This  pair  of  electrodes  was  used  exclusively 
in  all  our  first  series  of  experiments  dealing  with  body  currents. 
The  difference  of  potential  between  these  two  electrodes,  which  is 
indicated  by  a  deflection  of  50  mm.,  was  estimated  as  follows:  the 
current  is  95  X  10~9  amp.,  and  the  resistance  of  a  similar  pair  of 
electrode-tubes  and  the  column  of  fluid  connecting  them  was  found 
with  the  aid  of  the  Gordon  cell  to  be  about  1,060  ohms,  to  which 
must  be  added  the  resistance  of  the  galvanometer,  520  ohms.  By 
Ohm's  law  the  electromotive  difference  of  potential  is  approximately 
.00015  volt.  This  is  then  the  difference  of  potential  which  existed 
between  electrodes  2  and  3  at  the  time  of  this  test.  The  current 
was  not  driven  through  tubes  2  and  3  for  fear  of  polarization, 
but  all  the  tubes  were  the  same  size  and  shape  and  the  fluid  in  them 
of  the  same  concentration.  Their  resistance  was  therefore  approxi- 
mately equal.  Immediately  after  this  difference  of  potential  was 
tested  the  Y-tube  was  removed  and  the  subject  inserted  the  middle 
finger  of  his  right  hand  in  electrode  2  and  that  of  his  left  in  3. 
Thus  the  circuit  consisted  of  the  body  connected  in  series  with  the 
galvanometer  through  the  two  electrodes.  After  a  series  of  experi- 
ments in  muscular  contractions,  the  galvanometer  reading  was 


6  ELECTRICAL   PROCESSES   IN    THE   HUMAN   BODY 

—  300  mm.  The  fingers  were  then  reversed  with  respect  to  the 
tubes  and  the  reading  was  then  -f-  300.  At  other  times  similar  re- 
sults were  obtained,  as,  for  instance, — reading  with  fluid  connection 
between  electrodes  —  240,  reading  with  fingers  in  first  position 
4-  55,  in  reversed  position  —  98.  In  these  experiments  the  fact  that 
reversal  of  the  fingers  gives  a  reversal  of  the  deflection  shows  that 
there  is  a  difference  of  potential  between  the  fingers  generated  in 
the  body  which  is  greater  than  that  which  exists  between  the  two 
electrodes;  and  where  the  deflections  in  the  two  directions  are  ap- 
proximately equal,  the  body  potential  is  much  greater. 

The  ratio  between  the  two  may  be  calculated  as  follows:  The 
point  on  the  scale  midway  between  the  positive  and  negative  deflec- 
tions may  be  assumed  to  be  the  value  which  the  deflection  would 
have  if  the  electrode  potential  alone  were  acting  through  the  resist- 
ance of  the  body.  The  ratio  between  the  electrode  potential  and  the 
body  potential  is  equal  to  that  between  this  hypothetical  value  and 
its  difference  from  the  actual  deflection  caused  by  the  combined 
effects  of  electrode  and  body  potentials. 

The  resistance  of  the  body  may  be  calculated  from  the  experi- 
ments in  which  the  Gordon  cell  was  employed.  With  this  method 
the  sensitivity  of  the  galvanometer  was  reduced  to  .01  of  its  full 
value.  Under  these  conditions  the  deflections  usually  began  at 
about  400  mm.  and  rose  to  600  mm.  in  a  few  minutes,  seldom  going 
much  beyond  that  value.  The  e.m.f.  of  the  cell  used  is  .67  volts. 
From  this  it  is  calculated  that  a  deflection  of  500  mm.  indicates  a 
body  resistance  of  slightly  over  6,000  ohms,  a  deflection  of  600  mm. 
slightly  over  5,000  ohms.  From  this,  in  turn,  it  can  be  estimated 
that  under  average  conditions  of  body  resistance,  a  deflection  of 
500  mm.  with  the  galvanometer  at  its  full  sensitivity  connected  with 
the  hands  and  without  the  Gordon  cell,  indicates  a  body  potential 
of  about  .006  volt.  This  is  about  the  largest  deflection  we  have  ob- 
served in  the  present  experiments.  The  variations  in  body  resistance 
under  varying  conditions  are  such  that  these  values  are  only  rough 
approximations.  In  some  cases  the  resistance  was  found  to  be  as 
great  as  35,000  ohms. 

Thus  it  is  clear  that  a  difference  of  potential  exists  between  the 
fingers  which  produces  a  considerable  deflection  in  a  sensitive  gal- 
vanometer. But  it  does  not  follow  from  this  that  changes  in  the 
initial  deflection  following  emotional  stimuli  are  caused  by  changes 
in  potential,  for,  with  a  constant  potential  difference,  marked 
changes  in  resistance  would  produce  changes  in  deflection.  How- 
ever, examination  of  deflections  produced  in  the  word  tests  shows 
that  resistance  changes  can  not  alone  account  for  the  phenomena,  as 


PHYSICAL   AND   PHYSIOLOGICAL  7 

the  deflections  sometimes  increase  and  sometimes  decrease  in  re- 
sponse to  stimuli,  and,  furthermore,  they  often  cross  the  zero  point, 
indicating  an  actual  reversal  of  the  current;  and  in  general  the  size 
of  the  reaction  deflection  seemed  to  be  independent  of  the  amount  of 
the  initial  deflection.  Clearly  then,  the  deflections  following  stimuli 
are  due  in  part,  if  not  wholly,  to  changes  in  the  electro-motive  dif- 
ference of  potential  between  the  immersed  fingers. 

To  study  the  influence  of  resistance  changes,  the  second  method 
was  used,  namely,  the  introduction  into  the  circuit  of  the  Gordon 
cell  in  series  with  the  body  and  the  galvanometer.  Owing  to  the 
magnitude  of  the  current,  the  sensitivity  of  the  galvanometer  was 
reduced  one  hundred-fold  by  means  of  the  shunt.  As  stated  above, 
the  deflections  thus  caused  ranged  generally  between  500  and  600 
mm.  If  a  series  of  word  stimuli  was  then  tried,  the  deflections  which 
resulted  invariably  consisted  in  an  increase  in  the  initial  deflection. 
Their  average  magnitude  was  between  10  and  20  mm.  and  they 
rarely  exceeded  60  mm. ;  thus  the  maximum  deflections  indicated  an 
increase  of  about  10  per  cent,  in  the  current  passing  through  the 
body.  At  first  sight  it  might  appear  that  here  also  the  deflections 
are  due  to  electrical  potential  in  the  hands  augmenting  the  current 
of  the  cell,  but  the  fact  that  the  deflections  here  are  all  in  one  direc- 
tion, while  with  isopotential  electrodes  they  may  be  in  either,  is 
much  against  it.  Furthermore,  a  little  quantitative  study  shows 
that  a  difference  of  potential  of  the  magnitude  detected  with  iso- 
potential electrodes  could  not  possibly  produce  such  large  deflec- 
tions as  are  seen  with  the  cell  current.  The  galvanometer  being  at 
.01  of  its  full  sensitivity  which  is  employed  with  isopotential  elec- 
trodes, it  would  require  100  times  as  much  e.m.f .  to  produce  a  given 
deflection  as  it  does  to  produce  the  same  deflection  at  full  sensitiv- 
ity, and  yet  the  deflections  in  the  two  cases  are  found  to  be  of  about 
the  same  magnitude.  With  isopotential  electrodes  and  the  galvan- 
ometer at  full  sensitivity,  the  deflections  following  stimuli  rarely 
exceed  100  mm.  It  would  require  30  times  the  e.m.f.  which  this 
indicates  to  produce  a  change  of  30  mm.  with  the  sensitivity  re- 
duced, and  yet  30  mm.  is  by  no  means  an  infrequent  deflection  with 
the  Gordon  cell.  It  follows  from  this  that  electro-motive  changes 
can  not  account  for  the  deflections  observed  when  a  strong  outside 
current  is  used.  In  short,  emotional  reactions  are  accompanied  both 
by  changes  in  the  difference  of  potential  between  the  immersed 
fingers  and  by  changes  in  the  resistance  of  the  body. 

The  physiological  basis  of  the  electro-motive  phenomena  should 
be  considered  under  the  headings  already  enumerated.  "Action 
currents"  in  voluntary  muscles  are  a  very  improbable  cause,  for 


8  ELECTRICAL   PROCESSES   IN    THE   HUMAN   BODY 

contractions  of  the  voluntary  muscles  are  not  felt  by  the  subject  to 
occur  during  the  experiment  and  if  they  existed  they  would  not  be 
likely  to  escape  detection.  In  a  special  experiment,  the  effect  of 
contracting  voluntary  muscles  was  studied  as  follows :  The  subject, 
lying  motionless  with  the  hands  strapped  in  place  and  the  fingers  in 
the  isopotential  electrodes,  vigorously  exerted  antagonistic  muscles 
in  the  arm  without  moving  it,  and  gave  simultaneously  a  verbal 
signal.  The  observer  noted  and  recorded  the  deflections.  Deflec- 
tions regularly  followed  the  exertions,  differing  from  those  of  emo- 
tional stimuli  chiefly  in  having  a  shorter  latent  period.  They  fol- 
lowed the  exertions  by  an  interval  of  a  second  or  less,  whereas  in  the 
case  of  emotional  reactions  the  interval  is  about  three  seconds. 
In  this  series,  six  contractions  were  made  in  the  right  arm  and 
seven  in  the  left.  In  every  case,  the  deflection  following  was  in 
the  direction  which  indicated  a  relative  fall  of  potential  in  the 
finger  of  the  arm  in  which  the  muscles  were  exerted.  The  experi- 
ment was  repeated  with  two  subjects,  one  new  to  the  experiment, 
and  the  results  were  almost  uniformly  consistent  with  the  foregoing. 
This  harmonizes  with  the  view  that  the  deflections  in  this  case  were 
the  result  of  the  "action  currents"  of  the  muscles,  for  muscular 
contraction  is  characterized  by  the  release  of  negative  electrical 
charges.  The  deflections  in  these  experiments  were  rarely  greater 
than  40  mm.  and  yet  the  muscles  were  exerted  vigorously.  It  is, 
therefore,  extremely  improbable  that  contractions  of  voluntary 
muscles  so  slight  as  to  escape  the  subject's  attention  would  produce 
"action  currents"  great  enough  to  give  the  deflections  of  50  mm., 
sometimes  over  100  mm.,  which  follow  emotional  stimuli.  Volun- 
tary muscle,  therefore,  may  be  excluded  with  a  reasonable  degree  of 
certainty. 

Smooth  muscle  fibers  in  the  blood  vessel  walls  might  give  off 
"action  currents"  that  would  produce  the  deflections  and  the  curve 
of  their  contraction  is  much  more  like  the  curve  of  the  deflections 
than  is  that  of  striped  muscle.  The  experiment  of  Sidis  and  Kal- 
mus  with  Esmarch  bandages  in  preventing  effective  vaso-dilatation 
probably  had  little  effect  on  the  vaso-motor  nerve  impulses  or  on  the 
resulting  release  of  muscular  energy;  so  that  "action  currents"  may 
still  have  emanated  from  the  vascular  walls.  However,  other  evi- 
dence led  us  to  believe  that  this  plays  at  most  a  minor  part  in  pro- 
ducing the  deflections,  as  will  be  explained  later.  "Action  cur- 
rents" in  nerve  trunks  were  not  available  for  separate  study.  Like 
those  in  the  vascular  walls,  we  could  neither  prove  nor  disprove 
their  influence,  but  believe  that  they  also  play  at  most  a  minor  part. 

The  remaining  tissues  whose  "action  currents"  might  cause  the 


PHYSICAL   AND   PHYSIOLOGICAL  9 

deflections  are  the  glands  in  the  skin,  of  which  the  sweat-glands  are 
the  most  numerous  and  active.  The  literature  concerning  glandular 
"action  currents"  is  not  altogether  satisfactory.  Lillie,4  in  pre- 
senting a  hypothesis  to  explain  "action  currents"  on  the  grounds 
of  relative  permeability  to  ions  in  cell  membranes,  implies  that  cell 
activity  in  general  is  attended  by  a  release  of  negative  charges. 
Loeb5  implies  the  same  thing.  It  is  not  clear  whether  the  generaliza- 
tion is  based  on  muscles  and  nerve  alone  or  whether  glands  have 
also  been  shown  to  release  negative  charges.  "Waller,6  in  "The  Signs 
of  Life,"  shows  that  in  a  frog's  skin  the  "action  current"  is  out- 
going, that  is,  the  outer  surface  has  a  higher  potential  than  the 
inner.  He  confuses  his  electrical  terminology  and  his  explanation 
is  unsatisfactory.  Bayliss  and  Bradford7  showed  peculiar  varia- 
tions in  the  "action  currents"  of  the  skin  of  frogs  related  to  the 
season  of  the  year.  It  seems  that  these  phenomena  are  too  obscure 
to  be  of  value  as  a  basis  of  comparison  with  the  phenomena  in  hu- 
man skin.  Mendelsohn8  in  the  "Dictionnaire  de  Physiologic"  re- 
ports similar  findings  in  the  frog's  skin,  but  states  that  in  the  paw 
of  the  cat,  when  the  sciatic  nerve  is  stimulated,  there  is  an  in-going 
"action  current"  accompanying  the  secretion  of  sweat.  Waller  also 
quotes  the  previous  observation  of  Tarchanoff,  that  under  stimulation 
of  a  variety  of  types,  "parts  of  the  skin  in  which  sweat-glands  are 
most  abundant  become  negative  to  parts  containing  few  glands" 
(Lecture  VII.,  p.  124).  Thus  experimental  evidence  concerning 
mammalian  skin  containing  sweat-glands  shows  that  in  action  the 
surface  potential  is  relatively  lowered.  This  agrees  with  Lillie 's  im- 
plied generalization  concerning  the  release  of  negative  charges  in 
active  tissues,  and  it  is  probable  that  human  sweat-glands  would  show 
similar  ' '  action  currents. ' ' 

If  the  negative  charges  released  from  the  sweat-glands  produce 
electro-motive  phenomena,  we  should  expect  the  difference  of  po- 
tential between  the  hands  to  be  slight,  since  the  sweat-glands  of  the 
two  are,  as  far  as  we  know,  alike  and  should  produce  approximately 
equal  electrical  charges.  The  difference  of  potential  should  occur 
only  when  the  glandular  activity  in  one  hand  is  for  some  reason 
greater  than  that  in  the  other,  and  should  in  most  cases  cause  de- 

«R.  S.  Lillie,  "The  General  Biological  Significance  of  Changes  in  the 
Permeability  of  the  Surface  Layer  or  Plasma-membrane  of  Living  Cells," 
biological  Bulletin,  Vol.  XVII.,  pp.  188-208. 

5  J.  Loeb,  "  Dynamics  of  Living  Matter,"  pp.  68-09. 

"Richet's  Dictionnaire  de  Physiologic,  Mendelsohn's  article  on  "Electricity," 
Vol.  V.,  p.  350. 

'Bayliss  &  Bradford,  Journal  of  Physiology,  Vol.  VII.,  p.  217. 

8 Waller,  "The  Signs  of  Life,"  Lecture  IV. 


10  ELECTRICAL   PROCESSES   IN    THE   HUMAN   BODY 

flections  in  one  direction  as  often  as  in  the  other.  This  is  pre- 
cisely what  occurs  in  a  series  of  reactions ;  the  stimulus  may  be  fol- 
lowed by  a  positive  or  negative  deflection.  Neither  seems  to 
predominate;  the  galvanometer  may  cross  the  zero  point  several 
times  during  an  experiment.  It  is,  however,  characteristic  of  the 
deflections  that  they  tend  to  be  in  the  same  direction  as  their  im- 
mediate predecessors,  that  is,  there  is  apt  to  be  a  fairly  long  series 
of  consecutive  positive  deflections,  and  when  after  some  irregularity 
a  negative  deflection  appears,  it  is  apt  to  be  followed  by  a  series  of 
negative  deflections.  While  this  picture  agrees  with  what  we  should 
expect  if  sweat-gland  activity  were  the  cause,  we  should  expect  it 
just  as  much  if  the  "action  currents"  came  from  the  muscles  of 
blood  vessels.  Some  distinguishing  test  should  be  found.  Two 
methods  of  differentiating  were  tried;  one  was  to  compare  the  elec- 
trical potential  of  portions  of  the  integument  known  to  differ  in  the 
abundance  of  sweat-glands;  the  other  was  to  ascertain  the  influence 
of  drugs  on  the  phenomena. 

First  we  attempted  to  eliminate  the  sweat-glands  from  the  elec- 
trodes altogether  by  the  method  described  by  Sidis  and  Kalmus, 
coating  the  immersed  skin  with  shellac  and  paraffin,  leaving  only 
the  finger  nails  uncovered,  and  comparing  the  result  with  that  ob- 
tained with  the  bare  skin.  The  middle  fingers  were  covered  with 
two  coats  of  shellac  and  one  of  paraffin.  As  a  control  experiment, 
the  fingers  thus  coated  were  inserted  into  the  electrodes  before  the 
paraffin  was  scraped  from  the  finger  nails.  A  deflection  of  -j-  5  mm. 
resulted,  and  on  reversing  the  fingers  with  respect  to  the  electrodes 
the  deflection  was  reversed  to  —  6  mm.  This  showed  that  even  this 
insulation  was  not  complete,  since  the  difference  of  potential  be- 
tween the  fingers  caused  a  measurable  deflection.  With  the  fingers 
in  position,  the  effect  of  a  strong  stimulus  was  tried.  An  operatic 
graphophone  record  was  used  which  had  previously  given  rise  to 
large  deflections  under  the  usual  experimental  conditions.  At  the 
climax  of  the  piece,  where  the  subject  was  aware  of  the  most  intense 
affect,  a  deflection  of  2  mm.  was  noted.  This  observation  suggests 
that  the  conclusion  of  Sidis  and  Kalmus  that  "the  skin  has  little  or 
nothing  to  do  with  the  phenomena"  (because  when  the  skin  is  cov- 
ered with  shellac  and  paraffin,  leaving  only  the  finger  nails  ex- 
posed, deflections  are  still  obtained),  is  not  necessarily  correct.  Even 
if  the  insulation  had  been  perfect,  their  experiment  would  have 
proved  only  that  something  else  besides  sweat-glands  could  produce 
deflections ;  it  could  not  prove  that  sweat-glands  play  no  part.  After 
the  control  experiment,  we  scraped  the  finger  nails  bare,  leaving  the 
skin  coated  and  repeated  the  record,  then  repeated  it  a  third  time 


PHYSICAL   AND   PHYSIOLOGICAL  11 

with  the  fourth  fingers  (not  coated)  in  the  electrodes.  The  deflec- 
tions in  each  case  amounted  to  only  1  mm.,  which  indicated  either 
that  the  skin  resistance  was  too  high  or  the  electrical  reactions  too 
sluggish  at  that  time  to  furnish  any  satisfactory  data.  This  experi- 
ment seemed  to  us  important  and  would  have  been  well  worth  re- 
peating had  time  permitted.  It  was  immediately  followed  by  a 
similar  experiment  with  the  Gordon  cell  current,  which  threw  con- 
siderable light  on  the  resistance  phenomena  and  will  be  described 
under  that  heading. 

At  other  times  significant  results  were  obtained  by  immersing 
skin  surfaces  with  different  degrees  of  abundance  in  sweat-glands. 
If  active  sweat-glands  produce  negative  charges  which  cause  deflec- 
tions, increase  of  activity  must  cause  a  fall  of  potential  in  the  skin, 
and  the  more  active  the  glands,  the  greater  will  be  the  fall  of  poten- 
tial. If,  however,  in  two  skin  surfaces  unequally  supplied  with 
sweat-glands,  the  difference  lay  only  in  the  number  of  glands,  the 
individual  glands  all  being  equally  active,  the  two  surfaces  would 
be  electrically  equivalent,  for  the  glands  are  arranged,  so  to  speak, 
in  multiple  arc,  and  if  all  developed  the  same  potential,  the  re- 
sultant potential  of  the  whole  surface  would  be  no  greater  than  that 
of  a  single  gland.  A  surface  more  richly  supplied  with  glands  than 
another  can  only  undergo  a  greater  fall  of  potential  if  the  glands 
are  individually  more  active  as  well  as  more  numerous.  It  is  well 
known  that  the  palms  of  the  hands  are  richer  in  sweat-glands  than 
the  dorsal  surfaces,  whereas  there  is  little  difference  in  vascularity 
between  them.  This  fact  might  enable  us  to  secure  evidence  to  dif- 
ferentiate between  vascular  and  sweat-gland  activity.  The  relative 
potentials  of  these  surfaces  were  tested  by  the  use  of  soaked  cotton 
pressed  into  the  electrodes  (not  in  funnels).  With  the  dorsal  sur- 
faces of  the  two  hands  in  contact  with  the  fluid  of  the  two  elec- 
trodes, the  reading  was  —  5  mm. ;  with  both  palms  in  contact 
+  6  mm. ;  with  the  right  palm  and  left  back  —  36  mm. ;  with  the 
right  back  and  left  palm  -f-  21  mm.  In  all  these,  the  right  hand 
electrode  was  connected  with  the  positive  pole  of  the  galvanometer. 
The  experiment  was  repeated  with  similar  results.  This  indicates 
that  in  each  case  the  palmar  surface  has  a  lower  potential  than  the 
dorsal  surface  of  the  other  hand  and  the  difference  of  potential  is 
greater  than  that  which  exists  between  homologous  surfaces.  This 
evidence  accords  well  with  the  above-mentioned  observations  of 
Tarchanoff  cited  by  Waller,  in  which  similar  differences  of  potential 
were  seen  to  be  developed  under  the  influence  of  various  stimuli.  It 
distinctly  favors  the  view  that  sweat-glands  reduce  the  potential 
of  the  skin,  but  it  does  not  demonstrate  that  the  deflections  which 


12      ELECTRICAL  PROCESSES  IN  THE  HUMAN  BODY 

accompany  emotional  reactions  are  due  to  glandular  activity. 
To  test  this,  a  certain  graphophone  record,  which  at  a  certain  specific 
point  always  produced  an  appreciable  emotional  reaction  in  the  sub- 
ject, was  repeated  three  times;  first,  while  the  backs  of  the  hands 
were  in  contact  with  the  solutions,  then  with  both  palms,  and  finally, 
with  the  right  palm  and  left  back.  If  the  emotional  reaction  in  the 
three  cases  were  the  same,  we  should  expect  a  progressive  increase 
of  deflections,  for  in  the  more  active  palms  there  would  probably  be 
developed  a  greater  difference  of  potential  than  in  the  less  active 
dorsal  surfaces,  and  in  the  third  case,  the  difference  in  the  fall  of 
potential  between  the  active  palm  and  the  less  active  dorsal  surface 
should  be  the  greatest  of  the  three.  In  this  case  the  subject  re- 
ported as  might  be  expected,  that  the  emotional  reactions  were  not 
the  same,  but  progressively  less  each  time.  The  three  deflections  in 
their  order  were  3  mm.,  7  mm.,  and  3  mm.  Another  record  was  em- 
ployed, first  with  both  palms  in  contact,  then  with  the  right  palm 
and  left  dorsal  surface.  Two  strong  affects  were  felt  the  first  time, 
producing  deflections  of  5  mm.  and  7  mm.  The  second  time  the 
corresponding  points  in  the  music  caused  much  weaker  affects,  which 
gave  deflections  of  7  mm.  and  4  mm.  In  the  last  of  each  series, 
where  one  palm  and  one  dorsal  surface  were  employed,  the  affects 
were  marked  by  augmentation  of  the  existing  deflections,  which  fact 
harmonizes  with  the  assumption  that  the  deflections  are  caused  by 
increase  of  sweat-gland  activity.  Time  prevented  further  repeti- 
tions which  should  have  been  made  with  long  series  of  association 
words.  These  experiments,  though  wholly  inadequate  for  conclu- 
sions, suggest  that  during  emotional  reactions  there  is  probably  a 
greater  fall  of  potential  in  the  palm  than  in  the  dorsal  surface. 
They  should  be  repeated  many  times  before  substantial  inferences 
could  be  drawn.  The  best  test  would  be  to  use  two  galvanometers 
measuring  simultaneously  the  same  reactions  by  the  two  methods. 
It  may  be  well  here  to  mention  a  peculiar  phenomenon  noted  in 
studying  the  possibility  of  error  arising  from  varying  the  depth  of 
the  immersion  of  the  fingers.  It  was  found  that  when  the  subject 
moved  his  fingers  in  and  out  of  the  tubes,  varying  the  depth  of  im- 
mersion from  about  3  cm.  to  about  6  cm.,  a  change  in  the  deflection 
occurred  as  follows:  an  increase  in  the  depth  of  immersion  of  one 
finger  produced  a  change  in  the  same  direction  as  a  decrease  in  the 
depth  of  the  other.  This  was  verified  by  two  long  series  of  experi- 
ments on  two  subjects  and  in  both  the  changes  followed  this  prin- 
ciple in  almost  every  case.  The  few  exceptions,  11  out  of  a  total  of 
127,  may  easily  have  resulted  from  affects  which  are  not  subject  to 
control;  they  do  not  disprove  the  regularity  of  the  tendency.  This 


PHYSICAL   AND   PHYSIOLOGICAL  13 

phenomenon  can  not  be  explained  by  the  fact  that  greater  immersion 
decreases  the  resistance.  If  that  were  the  case,  increase  in  the  im- 
mersion of  either  finger  would  increase  the  deflection.  The  ex- 
planation suggested  by  Professor  T.  W.  Richards  is  that  near  the 
base  of  the  finger,  the  skin  has  a  lower  potential  than  near  the  top, 
and  this  appears  to  be  the  only  reasonable  explanation.  If  the  elec- 
trical potential  is  caused  by  sweat-glands,  it  would  indicate  that 
the  glands  near  the  base  of  the  finger  are  the  most  active. 

Another  experiment  should  be  mentioned  here  as  bearing  on 
this  phase  of  the  question.  A  series  of  word  tests  was  given  when 
the  subject  had  two  fingers  of  the  same  hand  in  the  two  electrodes. 
These  fingers  were  then  removed  and  corresponding  fingers  of  op- 
posite hands  were  introduced  and  another  series  of  word  tests  given. 
Again  two  fingers  of  the  same  hand  were  introduced  and  a  third 
series  given.  The  reaction  deflections  were  of  about  the  same  magni- 
tude in  all  three  series,  varying  from  1  mm.  to  20  mm.  In  the  first 
series,  the  initial  deflections  were  much  larger  than  in  the  other  two, 
and  the  reaction  deflections,  although  of  about  the  same  magnitude, 
differed  from  those  in  the  other  two  series  in  that  they  were  all 
positive,  thus  being  augmentations  of  the  initial  deflection  which 
was  positive,  whereas  in  the  two  latter  series,  some  were  positive  and 
some  negative.  This  would  indicate  that  in  the  first  series  one  finger 
was  inserted  relatively  deeper  than  the  other,  so  that  skin  of  lower 
potential  was  immersed.  The  uniformly  positive  reaction  deflec- 
tions here  are  significant,  as  tending  to  show  that  they  were  caused 
by  a  fall  of  potential  in  the  more  active  skin  surface  and  were  prob- 
ably produced  by  activity  of  those  glands  giving  rise  to  the  initial 
deflection.  In  the  other  two  series,  where  the  initial  deflection  was 
lower,  the  fingers  were  probably  immersed  to  more  nearly  equiva- 
lent depths  and  the  reaction  deflections  were  sometimes  positive  and 
sometimes  negative,  as  the  activity  of  one  or  the  other  finger  pre- 
dominated. The  fact  that  the  deflections  in  all  three  series  were 
of  approximately  the  same  magnitude  is  also  in  favor  of  the  view 
that  the  essential  activity  is  in  the  skin  or  superficial  layers  rather 
than  in  the  muscles  or  large  nerve  trunks,  for  these  would  be  apt  to 
influence  opposite  hands  far  more  differently  than  fingers  of  the 
same  hand. 

Further  evidence  on  the  relative  influence  of  glandular  and  vas- 
cular activity  was  sought  by  the  use  of  pilocarpine  and  atropine. 
Of  these  atropine  should  furnish  the  better  evidence  as  it  paralyzes 
the  nerve  endings  in  the  sweat-glands,  suppressing  the  secretion, 
while  it  somewhat  increases  vaso-dilatation,  and  if  the  essential 
activity  is  vascular,  it  undoubtedly  consists  in  dilatation,  not  con- 


14  ELECTRICAL   PROCESSES   IN    THE   HUMAN    BODY 

striction,  for  experiments  with  the  current  from  the  Gordon  cell  show 
that  affects  are  accompanied  by  decrease  in  body  resistance,  which 
could  hardly  result  from  vaso-constriction.  If  the  deflections  are 
chiefly  caused  by  vascular  action,  the  effect  of  atropine  upon  them 
would  be  difficult  to  predict  without  more  detailed  knowledge  of  its 
action  than  we  possess.  If  it  increased  the  susceptibility  of  the 
vessels  to  vaso-dilator  stimuli,  it  should  increase  the  deflections.  If 
it  caused  them  to  dilate  nearly  to  their  full  capacity,  it  should  dim- 
inish deflections  by  limiting  further  dilatation.  In  any  case,  the 
action  of  atropine  on  the  vascular  system  is  slight  and  it  should  not 
diminish  deflections  due  to  vascular  activity  to  any  marked  extent, 
whereas  its  paralyzing  action  on  the  sweat-glands  is  such  that  it 
should  greatly  diminish  deflections  caused  by  their  activity.  Pilo- 
carpine  stimulates  the  nerve  endings  in  the  sweat-glands,  increasing 
the  secretion;  it  also  causes  some  degree  of  vasodilatation,  which 
Cushny  considers  merely  incidental  to  the  increased  activity  of 
cutaneous  glands.  The  prediction  of  its  influence  on  vascular 
response  to  stimuli  is  as  indefinite  as  it  is  with  atropine  and  it  is 
uncertain  how  we  should  expect  it  to  influence  the  deflections  result- 
ing from  vascular  activity.  Moreover,  equal  uncertainty  attaches 
to  the  prediction  of  its  influence  on  deflections  assumed  to  result 
from  sweat-glands;  it  hinges  on  the  question  whether  the  stimula- 
tion of  the  drug  is  of  a  nature  which  renders  the  glands  more  sus- 
ceptible to  other  stimuli  or  less  so.  If  pilocarpine  merely  increases 
the  secretion  of  sweat  without  rendering  the  glands  more  responsive 
to  other  stimuli,  there  would  be  merely  an  approximately  symmet- 
rical fall  of  potential  in  both  fingers  which  probably  would  not  influ- 
ence the  deflections.  In  short,  if  the  sweat-glands  are  the  chief  cause 
of  deflections,  atropine  should  greatly  diminish  them,  while  the  effect 
of  pilocarpine  is  not  predictable.  If  vascular  changes  are  mainly 
responsible,  neither  atropine  nor  pilocarpine  should  produce  a  very 
marked  effect,  and  what  effect  they  did  produce  might  be  either 
increase  or  decrease.  The  method  of  testing  the  effects  of  these 
drugs  was  as  follows :  The  subject  reclined  as  usual  with  the  middle 
fingers  in  the  electrodes  and  responded  to  a  series  of  test  words,  the 
deflections  being  recorded  by  the  observer.  The  drug  was  then 
administered  subcutaneously  without  disturbing  the  position  of  the 
subject.  After  the  action  of  the  drug  had  begun  to  manifest  itself, 
a  second  series  of  words  was  given.  The  body  resistance  was  meas- 
ured before  and  after  the  experiment  by  means  of  the  Gordon  cell. 
The  experiment  with  pilocarpine  was  made  with  two  subjects.  In 
one  subject  it  appeared  to  increase  the  difference  in  potential  be- 
tween the  hands,  in  the  other  to  decrease  it;  in  both  subjects  the 


PHYSICAL   AND   PHYSIOLOGICAL  15 

average  magnitude  of  the  reaction  deflections  was  decreased.  Fur- 
ther details  are  omitted  as  the  uncertainty  regarding  the  exact  action 
of  this  drug  renders  the  results  of  little  significance  in  the  question 
at  hand.  The  only  evidence  of  value  in  the  drug  experiments  is  that 
furnished  by  atropine. 

The  effect  of  atropine  was  studied  by  the  same  method  as  that 
employed  with  pilocarpine.  In  the  first  subject  a  hundredth  of  a 
grain  was  given  after  the  first  series  of  words,  and  after  a  pause  of 
twenty  minutes  a  second  series  of  words  was  given.  Then  as  the 
drug  had  produced  no  symptoms,  a  fiftieth  of  a  grain  was  adminis- 
tered, and  after  fifteen  minutes,  dryness  of  the  mouth  being  appreci- 
able, a  third  series  of  words  was  tried.  The  results  were  as  follows. 
The  initial  or  resting  deflection  was  less  after  the  first  dose  of  atro- 
pine than  before,  but  after  the  second  dose,  it  increased.  The  ratios 
of  the  body  potential  to  the  electrode  potential  as  estimated  by  revers- 
ing the  fingers  were  40  to  26,  40  to  55,  and  85  to  35,  at  the  times  of 
the  three  series  respectively.  But  this -method  of  inference  can  not  be 
altogether  relied  upon,  especially  in  this  series  of  experiments  in 
which  electrodes  were  used  of  a  design  which  was  found  to  show 
changes  in  potential  when  subjected  to  disturbances  such  as  might 
occur  in  reversing  the  hands.  This  point  will  be  discussed  more 
fully  later.  The  average  of  the  reaction  deflections  in  the  first  series 
of  19  was  1.5  mm.  In  the  second  series  of  20,  after  the  first  dose,  it 
was  .8  mm.  In  the  third  series  of  24,  after  the  second  dose,  it  was 
.67  mm.  In  this  same  subject,  the  average  deflection  was  reduced 
from  1.7  to  1.5  by  pilocarpine.  In  the  second  subject,  the  same 
method  was  employed,  but  since  some  dryness  was  detected  after  the 
first  dose  of  .01  of  a  grain,  the  second  dose  consisted  of  only  .01 
instead  of  .02.  In  this  subject,  the  initial  deflection  decreased  after 
the  first  dose,  remaining  fairly  constant  throughout  the  second  and 
third  series.  Reversing  the  fingers  gave  such  irregular  results  as 
to  be  worthless  from  the  point  of  view  of  estimating  body  potential. 
This  was  probably  the  result  of  joggling  the  electrodes  in  shifting. 
The  average  of  24  reaction  deflections  in  the  first  word  series  was 
2.4  mm. ;  in  the  second,  after  one  dose  of  atropine,  the  average  of  21 
was  1  mm.;  after  the  second  dose,  the  reflex  was  practically  oblit- 
erated; only  4  out  of  12  stimuli  being  followed  by  any  deflections, 
and  none  exceeding  1  mm.  In  this  subject,  then,  as  well  as  in  the 
other,  the  reaction  deflections  were  reduced  more  by  atropine  than 
by  pilocarpine.  The  results  suggest  that  atropine  probably  reduced 
the  difference  of  potential  between  the  hands,  but  this  is  uncertain. 
It  clearly  reduced  to  a  marked  extent  the  deflections  following 
stimuli. 


16       ELECTRICAL  PROCESSES  IN  THE  HUMAN  BODY 

On  the  whole,  the  findings  concerning  the  influence  of  these 
drugs  on  initial  or  resting  difference  of  potential  between  the  hands 
are  of  little  value.  Moreover,  the  diminution  by  pilocarpine  of  the 
deflections  following  stimuli  is  of  doubtful  value  since  its  interpre- 
tation for  the  reasons  set  forth  above  is  not  clear.  The  one  signifi- 
cant result  is  the  marked  diminution  of  the  reaction  deflections  by 
atropine.  Since  this  drug  has  a  marked  paralyzing  effect  on  the 
sweat-glands,  but  has  comparatively  little  effect  on  the  vaso-motor 
system,  the  evidence  has  some  weight  in  the  question  at  issue,  and 
tends  strongly  to  support  the  view  that  the  sweat-glands  are  the 
chief  source  of  these  deflections. 

The  evidence  has  been  given  bearing  on  "action  currents"  of 
the  various  tissues  whose  activity  might  be  involved.  There  remain 
for  consideration  electro-chemical  activity  between  the  sweat  and  the 
electrolyte,  and  thermo-electrical  phenomena  at  surfaces  of  contact 
between  electrically  different  substances  within  the  tissues  or  at  their 
points  of  contact  with  the  electrolyte.  The  principal  electrolyte  in 
sweat  is  sodium  chloride.  Electro-chemical  action  between  this  and 
potassium  chloride  which  surrounds  the  fingers  in  these  experiments 
is  so  slight  that  it  is  highly  improbable  that  it  constitutes  an  impor- 
tant factor  in  the  deflections  under  consideration.  The  same  is  true 
of  thermo-electrical  phenomena,  for  the  substances  within  the  tissues 
are  such  that  even  with  large  temperature  changes  at  their  points 
of  contact,  the  e.m.f .  developed  in  this  way  would  be  very  slight  and 
it  is  probable  that  the  temperature  change  in  active  tissues  is  ex- 
tremely small.  That  thermo-electrical  phenomena  at  the  point  of 
contact  between  the  tissues  and  the  electrolyte  are  not  of  much  con- 
sequence is  indicated  by  the  fact  that  deflections  produced  when  the 
electrodes  were  maintained  at  body  temperature  by  a  thermostat 
were  not  found  to  differ  in  any  way  from  those  produced  when  the 
electrodes  were  at  room  temperature,  several  degrees  cooler  than  the 
body. 

The  foregoing  statement  of  evidence  and  inferences  concerning 
the  causation  of  electro-motive  changes  in  the  hands  practically 
eliminates  all  factors  except  "action  currents"  in  the  muscles  of  the 
vascular  system  and  in  sweat-glands  from  playing  any  considerable 
part.  The  various  facts  noted  all  tend  to  support  the  view  that 
sweat-gland  activity  is  the  most  important  factor,  although  none 
can  be  said  definitely  to  prove  it.  None  of  the  facts  seem  to  oppose 
this  view  in  any  way.  Obliteration  of  the  deflections  by  atropine 
supports  the  sweat-gland  hypothesis  fairly  strongly  and  tends  to 
indicate  that  if  vaso-motor  activity  plays  any  part,  it  is  at  most  a 
small  one. 


PHYSICAL   AND  PHYSIOLOGICAL  17 

The  resistance  changes  must  depend  chiefly  on  vaso-dilatation 
or  on  sweat-gland  activity.  This  assumption  is  due  not  only  to  the 
absence  of  any  other  probable  cause,  but  is  supported  by  the  fol- 
lowing experiment.  The  resistance  of  the  body  was  measured  by 
the  use  of  the  Gordon  cell,  with  the  middle  fingers  of  the  two  hands 
immersed  in  the  electrodes,  and  was  found  to  be  about  18,000  ohms. 
The  fingers  were  then  soaked  in  warm  water  and  again  inserted  in 
the  electrodes.  The  resistance  was  then  found  to  be  about  14,000 
ohms.  Next  the  two  index  fingers,  which  had  not  been  previously 
soaked,  were  inserted  and  the  resistance  was  found  to  be  35,000  ohms. 
Then  the  index  finger  and  the  fourth  finger  of  the  same  hand  were 
introduced  into  the  electrodes  and  the  resistance  was  found  to  be 
31,000  ohms.  It  was  then  noted  that  when  the  index  finger  and  the 
middle  finger  of  the  same  hand  were  introduced  into  the  electrodes, 
the  middle  finger  only  having  been  previously  soaked,  the  resistance 
was  higher  than  when  the  middle  fingers  of  the  opposite  hands,  both 
of  which  had  been  previously  soaked,  were  employed.  This  shows 
that  by  far  the  greater  part  of  the  body  resistance  is  in  the  skin  or 
superficial  layers.  The  resistance  of  the  structures  within  the  skin 
forms  so  small  a  part  of  the  total  resistance  that  it  would  have  to  be 
enormously  reduced  during  an  emotional  reaction  to  produce  the 
changes  often  noted  amounting  to  10  per  cent,  of  the  total  resistance. 
It  is  impossible  that  there  should  be  sufficient  change  in  internal  re- 
sistance to  produce  the  observed  deflections.  Therefore,  the  cause  of 
the  resistance  changes  noted  must  lie  chiefly  in  the  surface  layers. 

We  have  then  to  consider  the  relative  importance  of  vaso-dilata- 
tion and  sweat-gland  activity  in  the  causation  of  the  observed  resis- 
tance changes.  It  has  been  noted  that  the  deflections  following 
emotional  stimuli  with  the  cell  current  always  marked  a  lowering  of 
body  resistance.  Immediately  after  the  experiment  already  de- 
scribed (p.  10),  in  which  the  skin  was  coated  with  shellac  and  par- 
affin in  the  study  of  potential  changes  in  the  hands,  the  Gordon  cell 
was  introduced  and  a  similar  experiment  was  performed  to  throw 
light  on  the  corresponding  resistance  changes.  The  galvanometer 
was  shunted  as  usual  to  .01  of  its  full  sensitivity.  The  fourth  fingers 
(not  coated)  were  inserted  in  the  electrodes  and  a  deflection  of  195 
mm.  was  observed.  The  middle  fingers,  coated  as  already  described 
with  shellac  and  paraffin,  except  on  the  surface  of  the  nails,  were 
then  inserted.  A  deflection  of  58  mm.  resulted.  A  graphophone 
record  was  then  played  which  at  a  definite  point  produced  a  fairly 
marked  emotional  reaction  in  the  subject.  At  the  time  the  affect 
was  felt,  the  galvanometer  reading  rose  from  64  mm.,  where  it  had 
gone  at  the  beginning  of  the  record,  to  65  mm.  The  index  fingers 


18  ELECTRICAL   PROCESSES   IN    THE   HUMAN   BODY 

(not  coated)  were  then  inserted,  and  a  deflection  of  100  mm.  re- 
sulted, rising  during  the  first  part  of  the  music  to  170  mm.  and  at 
the  point  where  the  marked  affect  was  felt,  to  210  mm.  The  nails  of 
the  middle  fingers  were  then  coated  with  paraffin,  and  the  fingers 
inserted  as  before.  The  deflection  resulting  was  33  mm.  The  same 
record  was  then  played,  and  at  the  point  where  the  marked  affect 
was  felt,  the  galvanometer  reading  which  had  remained  at  33  mm., 
rose  to  35  mm.  Another  graphophone  record  was  then  played  in 
which  a  still  more  definite  emotional  reaction  occurred  at  a  certain 
point.  The  galvanometer  reading  during  the  early  part  of  the  music 
was  26  mm.  When  the  affect  occurred,  it  rose  to  29  mm.  This  was 
repeated  without  removal  of  the  fingers.  The  affect  was  marked  by 
a  rise  from  25  mm.  to  28  mm.  The  paraffin  was  then  scraped  from 
the  finger  nails,  leaving  the  remainder  of  the  skin  still  coated  and 
the  deflection  following  their  insertion  was  136  mm.  The  record 
was  repeated  and  when  the  affect  occurred,  the  reading  rose  from 
140  mm.  to  144  mm.  The  index  fingers  (not  coated)  were  then  in- 
serted and  the  galvanometer  read  200  mm.  The  record  was  re- 
peated and  when  the  affect  occurred,  the  deflection  rose  from  210 
mm.  to  265  mm.  In  these  experiments,  the  deflections  are  inversely 
proportional  to  the  body  resistance;  thus  a  deflection  of  100  mm. 
indicated  a  body  resistance  of  35,000  ohms;  a  deflection  of  25  mm., 
a  resistance  of  140,000  ohms.  It  is  clear  that  very  considerable  con- 
duction occurs  through  the  finger  nails,  since  covering  them  with 
paraffin  reduced  the  deflection  from  60  mm.  to  30  mm.,  and  scraping 
them  bare  again  raised  it  from  26  mm.  to  136  mm.  The  highly  vas- 
cular tissues  beneath  the  finger  nails  being  brought  into  fairly  close 
relation  with  the  electrolyte,  we  should  expect  that  if  vaso-dilatation 
were  the  chief  factor  in  the  reactions,  the  deflections  marking  an 
affect  would  be  about  the  same  percentage  of  the  total  deflection  as 
when  the  skin  is  exposed.  In  the  first  experiments  with  the  finger 
nails  bare  and  the  remainder  of  the  fingers  coated,  we  note  an  in- 
crease of  the  initial  deflection  of  1  mm.,  or  about  2  per  cent.  With 
the  bare  fingers,  the  conduction  was  only  increased  three  fold,  but 
the  same  passage  in  the  music  caused  a  deflection  of  40  mm.,  over 
20  per  cent,  of  the  total,  and  yet  the  affect  was  probably  less  in  the 
second  case  than  in  the  first.  With  the  second  graphophone  record, 
it  was  shown  that  even  when  the  fingers  were  completely  coated,  a 
deflection  of  3  mm.  occurred  in  each  of  two  successive  tests ;  with  the 
finger  nails  scraped  bare,  although  the  total  deflection  was  increased 
from  25  mm.  to  130  mm.  due  to  conduction  through  the  finger  nails, 
the  deflection  marking  the  affect  was  only  4  mm.  With  the  bare 
fingers,  although  the  total  conduction  was  increased  only  in  a  ratio  of 


PHYSICAL   AND   PHYSIOLOGICAL  19 

200  to  130,  the  affect  (by  this  time  distinctly  weakened  by  repetitions 
of  the  stimulus)  caused  a  deflection  of  55  mm.  Thus  it  is  seen  that  in- 
creasing the  conduction  through  a  vascular  region  without  sweat- 
glands  did  not  cause  an  increase  in  the  reaction  deflections,  whereas 
the  exposure  of  skin  containing  sweat-glands  to  the  electrolyte 
greatly  increased  these  deflections.  It  is  not  even  necessary  to  as- 
sume that  vaso-dilatation  caused  the  small  deflections  observed  when 
the  finger  nails  were  bare,  since  approximately  equal  deflections 
were  observed  when  they  were  covered,  and  may  well  have  been 
caused  by  the  sweat-glands  in  the  skin,  since  the  insulation  has  been 
shown  to  be  incomplete.  Thus,  this  experiment  furnishes  strong 
evidence  tending  to  prove  that  the  resistance  changes  are  chiefly,  if 
not  wholly,  due  to  sweat-gland  activity. 

The  evidence  furnished  by  drugs  concerning  the  resistance 
changes  was  slight.  In  neither  subject  were  word  tests  employed 
with  the  cell  current  in  the  pilocarpine  experiments.  In  each,  how- 
ever, the  resistance  was  measured  before  and  after  the  administra- 
tion of  the  drug.  In  one,  there  was  a  slight  increase ;  in  the  other, 
a  considerable  decrease.  With  atropine,  in  only  one  subject  was 
the  resistance  measured  before  and  after,  and  in  this  case,  it  re- 
mained practically  the  same.  In  the  other  subject,  the  resistance 
was  not  measured  before  the  administration  of  the  drug ;  but  at  the 
end  of  the  experiment,  after  the  obliteration  of  the  deflections 
caused  by  body  currents  had  been  shown,  the  cell  was  introduced, 
and  the  deflections  following  the  test  words  were  almost  as  com- 
pletely obliterated.  If  the  reduction  of  resistance  is  due  to  sweat- 
gland  activity,  we  should  expect  a  similar  reduction  to  follow  the 
administration  of  pilocarpine.  That  this  was  not  so  in  one  of  the 
subjects,  would  seem  at  first  sight  to  militate  against  the  sweat-gland 
hypothesis.  However,  it  is  perfectly  possible  that  the  way  in  which 
the  sweat-glands  lower  resistance  is  by  the  temporary  distention  of 
sweat  tubules  with  secretion  following  a  fairly  sudden  access  of  ac- 
tivity. It  is  quite  conceivable  that  the  production  of  sweat  under 
the  influence  of  pilocarpine  is  so  gradual  that  the  tubules  carry  off 
the  sweat  as  fast  as  it  is  produced,  and  that  the  distention  is,  there- 
fore, not  appreciable.  The  failure  of  atropine  to  increase  the  re- 
sistance may  likewise  be  due  to  the  fact  that  the  tubules  are  normally 
empty  and  the  paralysis  of  the  sweat-glands  can  not,  therefore,  make 
them  any  emptier.  The  fact  that  the  sudden  fall  of  resistance  fol- 
lowing stimuli  was  obliterated  by  atropine  is  strong  evidence  that  it 
is  caused  by  sweat-gland  activity.  Furthermore,  a  study  of  the 
structure  of  the  skin  suggests  that  on  physical  grounds  it  is  prob- 
able that  a  marked  fall  of  resistance  could  be  more  easily  accounted 


20  ELECTRICAL   PROCESSES   IN    THE   HUMAN    BODY 

for  by  the  filling  of  tubules  with  sweat  and  the  resulting  estab- 
lishment of  many  columns  of  conducting  fluid  than  by  the  greater 
abundance  of  blood  beneath  the  skin,  which  results  from  vaso-dilata- 
tion.  It  seems  highly  probably,  then,  that  the  resistance  changes 
are  caused  chiefly,  if  not  wholly,  by  the  activity  of  the  sweat-glands. 

It  has  been  demonstrated  that  emotional  states  are  marked  by 
electro-motive  changes  in  the  skin  and  by  lowering  of  body  resis- 
tance. It  has  been  shown  that  the  electro-motive  changes  probably 
result  chiefly  from  sweat-gland  activity  and  that  there  is  somewhat 
greater  probability  that  the  same  activity  is  the  cause  of  the  resis- 
tance change.  The  probability  in  both  cases  is  reinforced  by  the 
harmony  of  these  findings.  It  is  further  significant  that  the  de- 
flections produced  in  the  two  ways  are  similar  in  character.  In 
each  case,  the  deflection  usually  begins  after  a  latent  period  of  about 
3  seconds,  and  rises  rapidly  to  a  maximum  from  which  it  soon  starts 
to  fall  gradually  toward  the  starting-point.  There  is  this  difference ; 
the  resistance  deflections  are  much  more  regular  and  almost  always 
adhere  closely  to  this  type;  the  deflections  caused  by  electro-motive 
changes  are  irregular,  the  latent  period  may  be  prolonged  and  the 
main  deflection  may  be  preceded  by  a  short  preliminary  deflection 
in  the  opposite  direction ;  and  instead  of  returning  regularly  almost 
to  the  starting-point  after  the  maximum  is  reached,  it  may  remain 
there,  or  after  a  pause  go  even  higher.  These  facts  are  in  harmony 
with  the  supposed  difference  in  the  causation  of  the  two  types  of 
deflection.  The  tubules,  suddenly  distended  with  fluid,  would  be 
expected  to  empty  themselves  gradually  and  at  a  uniform  rate,  as 
their  elastic  walls  contracted,  and  the  original  resistance  would  then 
be  reestablished.  The  difference  of  potential  set  up  between  the 
fingers  by  variable  differences  in  the  activity  of  the  two  skin  surfaces 
could  not  be  expected  to  subside  with  the  same  regularity. 

It  can  not  be  said  that  anything  final  is  established  by  these  few 
experiments,  where  so  many  intricate  and  inseparable  factors  are 
involved;  but  it  seems  eminently  probable  in  view  of  the  harmony 
of  the  evidence  that  the  psycho-physical  galvanic  reflex  is  principally 
the  result  of  a  single  physiological  activity,  the  secretion  of  sweat, 
which  manifests  itself  physically  in  two  ways,  by  changing  the  elec- 
trical potential  of  the  surfaces  of  the  body  and  by  lowering  the  re- 
sistance of  the  skin. 


II.  SOURCES  OF  ERROR  IN  PRACTICAL  APPLICATIONS 

Experiments  were  conducted  to  study  the  various  sources  of 
error  which  should  be  met  in  applying  the  deflections  to  the  analysis 
of  emotional  reactions.  An  effort  was  made  to  determine  the  mag- 
nitude of  error  which  might  be  expected  from  unconscious  motions 
of  the  fingers  which  would  change  the  depth  of  immersion.  The 
subject  stood  before  the  tubes  and  moved  his  fingers  in  and  out  of 
the  solution,  varying  the  depth  of  immersion  from  about  3  cm.  to 
about  6  cm.  The  character  of  the  changes  resulting  has  been  de- 
scribed and  discussed  in  connection  with  the  electrical  potential  of 
the  skin.  What  concerns  us  now  is  the  magnitude  of  the  deflections. 
The  maximum  deflection  produced  by  this  change  in  the  depth  of 
immersion  of  one  finger,  after  the  initial  changes  due  to  soaking  had 
ceased,  was  40  mm.  with  one  subject,  and  28  mm.  with  the  other. 
From  this,  it  may  be  inferred  that  motions  of  the  fingers  which  were 
too  small  to  be  perceived  by  the  subject  would  not  cause  any  con- 
siderable error,  and  even  motions  as  great  as  the  apparatus  would 
allow  would  not  produce  deflections  large  enough  to  simulate  or 
obscure  the  reaction  deflection  of  a  moderate  affect,  owing  also  to  the 
differences  in  latent  period.1 

An  attempt  was  made  to  ascertain  whether  a  convenient  means 
of  insulation  could  be  found  which  could  be  applied  to  the  skin  at 
the  level  of  immersion,  so  that  the  surface  in  actual  contact  with  the 
fluid  should  be  absolutely  constant.  Shellac  was  found  to  be  wholly 
inadequate,  as  even  when  the  fingers  to  be  immersed  were  com- 
pletely covered  with  two  coats,  the  first  drying  before  the  second 
was  applied,  and  the  second  drying  before  testing,  deflections  re- 
sulted almost  as  great  as  those  obtained  without  insulation.  It  has 
already  been  stated  that  even  when  a  coat  of  paraffin  was  added  to 
shellac,  insulation  was  not  complete.  When  the  fingers  completely 
covered  by  rubber  cots  were  placed  in  the  electrodes,  no  deflection 
was  produced.  The  insulation  was  here  complete.  Rubber  cots 
were  then  applied  with  their  tips  cut  off  so  that  a  constant  surface 
was  exposed  beneath  the  fluid.  Changes  in  the  depth  of  immersion 
here  caused  changes  in  the  deflections  similar  to  those  thus  caused 
without  insulation,  but  much  smaller.  The  explanation  of  this  is 
difficult.  If  any  fluid  worked  up  under  the  edge  of  the  rubber,  it 
must  have  been  an  exceedingly  thin  film  and  its  resistance  very 
1  Cf.  Peterson  and  Jung,  Brain,  XXX.,  p.  159. 
21 


22  ELECTRICAL   PROCESSES   IN   THE   HUMAN   BODY 

high,  yet  it  might  conceivably  account  for  the  changes.  The  de- 
crease in  resistance  in  the  fluid  resulting  from  bringing  the  finger 
nearer  to  the  mercury  could  not  amount  to  more  than  4  or  5  ohms, 
and  this  compared  to  the  5,000  or  6,000  ohms  in  the  body  is  too 
small  to  account  for  the  changes.  It  is  possible  that  the  increase  in 
pressure  from  deeper  immersion  causes  a  better  saturation  of  the 
skin  or  in  some  such  way  improves  conduction.  It  was  concluded 
from  these  experiments  that  the  available  methods  of  insulation 
serve  rather  to  give  a  false  sense  of  constancy  of  contact  than  to 
give  any  real  constancy,  and  it  seemed,  therefore,  better  to  trust  to 
the  stationary  position  of  the  hands,  which  is  sufficiently  reliable 
for  practical  purposes. 

The  question  of  thermo-electrical  phenomena  brings  up  important 
considerations  which  were  dealt  with  as  follows.  The  temperature 
coefficient  of  the  calomel  electrode  is  .0006  volt.  That  is,  if  one  elec- 
trode becomes  heated  1°  C.  more  than  the  other,  the  potential  differ- 
ence between  them  becomes  modified  to  the  extent  of  .0006  volt, 
which  is  about  the  average  difference  of  potential  produced  by  the 
body,  and  .1  of  the  approximate  maximum  in  our  experiments. 
When  the  fingers  are  inserted  in  the  tubes  whose  temperature  is 
approximately  that  of  the  surrounding  air,  the  fluid  at  the  surface 
is  warmed.  Under  these  conditions,  convection  is  not  favored,  and 
the  heating  of  the  lower  portions  of  the  tubes  containing  the  calomel 
and  mercury  is  very  slow.  However,  some  change  of  temperature 
occurs  throughout  the  tubes,  and  though  this  tends  to  be  nearly  the 
same  in  the  two  electrodes,  it  is  'probable  that  in  a  fairly  long  experi- 
ment one  electrode  will  be  heated  somewhat  more  than  the  other, 
perhaps  to  the  extent  of  one  or  two  degrees  centigrade.  Assuming 
all  conditions  within  the  body  to  remain  constant  during  the  experi- 
ment and  the  body  resistance  to  be  6,000  ohms,  a  change  of  1°  C. 
would  cause  a  change  of  50  mm.  in  the  deflection  of  the  galvanom- 
eter. These  figures  were  verified  by  the  following  experiment. 
The  temperature  of  one  electrode  was  raised  to  35°  C.,  the  other 
being  maintained  at  20°  C.  The  galvanometric  deflection,  which 
varied  between  20  and  40  mm.,  when  the  electrodes  were  at  the  same 
temperature,  was  raised  to  over  700  mm.  by  this  change.  This  indi- 
cates a  rise  in  the  deflections  of  47  mm.  per  degree,  which  is  in  close 
agreement  with  the  calculated  value.  If  any  such  change  resulted 
from  warming  of  the  electrodes  by  the  fingers,  it  would  occur  gradu- 
ally during  the  course  of  the  experiment,  and  hence  would  not  impair 
the  value  of  a  given  electric  bodily  reaction  whose  duration  is  only 
a  few  seconds;  but  it  would  change  the  starting-point  of  the  indi- 
vidual deflections  and  possibly  falsify  the  relation  between  those  at 


SOURCES   OF  ERROR  23 

the  beginning  and  those  at  the  end  of  the  series.  It,  moreover,  con- 
fuses the  problem  of  the  causation  of  the  deflections  by  the  addition 
of  a  new  factor.  To  measure  the  actual  effect  of  heat  from  the 
fingers  upon  the  deflection,  two  of  the  electrodes  (Nos.  I.  and  V.) 
were  connected  with  the  galvanometer  and  the  circuit  closed  with  the 
electrolyte  in  the  Y-tube.  The  subject  then  inserted  his  fingers  into 
the  tubes,  completely  insulated  from  the  fluid  by  thin  rubber  cots, 
the  Y-tube  being  still  in  place  to  complete  the  circuit.  Subsequent 
changes  in  the  deflection  were  thus  due  solely  to  heat  acting  in  two 
ways,  through  the  change  in  electrode  potential  and  through  lower- 
ing the  resistance  of  the  electrolyte.  In  ten  minutes  the  deflection 
rose  to  105  mm.  The  finger  was  then  withdrawn  from  one  of  the 
tubes  (No.  V.)  ;  in  five  minutes  more  the  reading  was  110.  The 
remaining  finger  was  then  transferred  from  tube  I.  to  tube  V.,  and 
after  eight  minutes,  the  reading  was  125.  The  further  changes  were 
as  follows:  finger  transferred  to  I.,  after  six  minutes,  148  mm.; 
transferred  to  V.,  after  ten  minutes,  144;  transferred  to  I.,  after 
five  minutes,  160.  At  this  point,  the  fingers  were  removed  and  the 
bottom  of  tube  V.  was  grasped  with  the  hand.  This  caused  a  com- 
paratively rapid  rise  to  190  mm.  Tube  I.  was  then  grasped  with  a 
resulting  fall  in  the  deflection.  This  experiment  shows  that  the 
effect  of  warming  with  the  inserted  finger  was  to  materially  lower 
the  resistance  of  the  electrolyte,  while  owing  to  the  lack  of  convec- 
tion, no  appreciable  change  in  potential  occurred.  The  potential 
change  which  depends  upon  the  temperature  of  the  mercury,  ap- 
peared only  when  the  bottom  of  the  tube  was  grasped.  When  the 
Y-tube  is  replaced  in  the  circuit  by  the  human  body,  the  change  in 
the  resistance  of  the  electrolyte  becomes  negligible.  It  seems,  there- 
fore, that  for  most  practical  purposes,  experiments  conducted  at 
room  temperature  are  satisfactory.  But  for  the  sake  of  eliminating 
as  far  as  possible  the  thermal  factor  in  studying  the  cause  and  extent 
of  the  phenomena,  it  seemed  worth  while  to  introduce  a  thermostat 
to  keep  the  electrodes  as  nearly  as  possible  at  body  temperature. 
Another  advantage  of  this  procedure  is  that  it  prevents  the  increase 
of  skin  resistance,  which  is  apt  to  occur  if  the  circulation  is  sluggish 
when  the  skin  is  in  contact  with  cool  fluid. 

A  thermostat  was,  therefore,  arranged  consisting  of  a  long  iron 
tank  full  of  water  placed  transversely  on  the  floor  under  the  massage 
table,  heated  by  an  electric  coil  and  regulated  by  an  acetone  reservoir 
with  platinum  and  mercury  contact  and  a  rheostat.  An  electric 
stirrer  was  introduced  and  it  was  found  that  with  this  apparatus 
the  variation  in  temperature  did  not  exceed  one  or  two  tenths  of  a 
degree  centigrade.  It  was  necessary  with  the  thermostat  to  employ 


24  ELECTRICAL   PROCESSES   IN    THE   HUMAN   BODY 

electrode  tubes  of  a  new  design,  for,  if  the  original  tubes  were  im- 
mersed in  the  water  bath,  the  platinum  wires  sealed  into  them  at  the 
bottom  point  could  not  be  effectively  insulated  from  the  water  and  a 
short  circuit  would  result.  For  this  reason,  tubes  were  made  having 
a  diameter  of  5  cm.  for  most  of  their  length,  but  narrowing  at  the 
bottom  to  a  diameter  of  2  cm.  A  short  platinum  wire  was  welded 
to  the  end  of  a  copper  wire  and  passed  through  a  slender  glass  tube 
until  only  the  platinum  protruded  from  the  end.  This  end  of  the 
glass  tube  was  sealed  off,  and  bent  upwards  at  a  sharp  angle.  This 
glass  tube  was  placed  in  the  larger  electrode  tube  with  the  pro- 
truding platinum  point  at  the  bottom  and  mercury  was  added  till 
the  platinum  was  wholly  covered;  next  above  this  was  a  layer  of 
calomel  and  the  tube  was  filled  with  potassium  chloride.  As  with 
the  other  tubes,  both  the  calomel  and  potassium  chloride  had  been 
prepared  in  the  usual  way  for  non-polarizable  electrodes.  In  this 
way,  the  current  was  led  off  above  the  level  of  the  water  bath,  and  a 
short  circuit  was  avoided.  In  the  course  of  the  experiments  with 
these  electrodes,  a  new  and  serious  source  of  error  appeared,  to  which 
allusion  has  already  been  made.  Although  the  inner  tubes  contain- 
ing the  conducting  wires  were  tied  in  such  a  way  as  to  hold  them  as 
securely  as  possible  in  one  position,  it  was  found  impossible  to  wholly 
immobilize  them.  It  might  be  possible  to  seal  them  so  as  to  do  so. 
"When  any  joggling  occurred,  moving  the  platinum  contacts  within 
the  mercury,  changes  in  electrode  potential  resulted,  showing  them- 
selves by  considerable  deflections  of  the  galvanometer.  As  long  as 
care  was  taken  to  avoid  joggling,  these  changes  did  not  occur.  These 
tubes  were  used  in  most  of  the  later  experiments  and  it  is  believed 
that  error  was  not  permitted  to  occur  in  this  way  except  in  the 
instance  already  mentioned.  However,  the  danger  of  error  arising 
in  this  way  during  the  conduct  of  experiments  is  considerable,  espe- 
cially if  cooperation  is  at  all  questionable.  Since  the  potential 
changes  arising  from  warming  the  electrodes  are  of  no  practical  con- 
sequence, it  seems  advisable  in  the  great  majority  of  experiments  to 
dispense  with  the  thermostat  and  use  electrode  tubes  such  as  were 
first  described  with  platinum  wires  sealed  into  the  bottom  points, 
thus  eliminating  the  more  serious  source  of  error. 

In  relation  to  such  reactions  as  the  emotional,  it  is  reasonable  to 
expect  greater  uniformity  in  the  use  of  a  cell  current,  if  our  con- 
clusions regarding  the  physiology  of  the  phenomena  are  correct,  for, 
as  has  been  pointed  out,  deflections  with  isopotential  electrodes  de- 
pend upon  the  skin  surfaces  of  the  two  fingers  being  differently 
affected.  It  is  obvious  that  an  intense  affect  stimulating  the  sweat- 
glands  of  two  fingers  to  great  activity  might  stimulate  them  almost 


SOURCES   OF  ERROR  25 

equally;  whereas,  a  slight  affect  only  weakly  stimulating  the  sweat- 
glands  might  happen  to  stimulate  those  on  one  side  much  more  than 
those  on  the  other.  Thus  the  intense  affect  would  cause  a  smaller 
deflection  than  the  slight  affect.  In  a  long  series  of  tests,  however, 
the  average  of  the  deflections  following  strong  stimuli  would  tend 
to  be  greater  than  the  average  of  those  following  weak  stimuli,  for 
with  large  potential  changes  in  the  skin,  the  difference  between  the 
two  sides  would  in  a  majority  of  cases  be  greater  than  with  small 
potential  changes.  With  the  cell  current,  we  should  expect  more 
regularity,  for  the  deflections  are  caused  by  lowering  of  the  resis- 
tance which  results  from  the  secretion  of  sweat  and  this  should  occur 
invariably  with  strong  affects.  Just  such  a  difference  was  noted 
between  the  body  current  and  the  cell  current.  With  the  former, 
marked  affects  occasionally  occurred,  showing  only  small  deflections, 
whereas  with  the  cell  current,  this  was  almost  never  the  case.  It 
would  seem  to  follow  from  this  that  the  use  of  the  cell  current  is  the 
more  reliable  method  of  measuring  affects. 


III.     ON  THE  REACTION  DEFLECTION  AS  BELATED  TO 

THE  INTENSITY  OF  EMOTIONAL  RESPONSE   WITH 

SPECIAL  REFERENCE  TO  THE  ASSOCIATION 

EXPERIMENT 

The  purpose  of  the  accompanying  remarks  is  to  further  describe 
a  number  of  experiments  that  were  made  with  a  view  to  testing  the 
criteria  of  the  emotional  reactions  in  the  association  experiment. 
No  one  who  has  followed  the  recent  tendencies  in  the  literature  of 
the  association  test  can  fail  to  appreciate  how  closely  these  newer 
viewpoints  are  bound  up  with  questions  of  affective  reaction ;  but  it 
is  in  every  way  desirable  to  study  these  reactions  as  quantitatively 
as  may  be,  though  the  means  at  present  to  our  hands  are  far  from 
perfect. 

Under  present  conditions  the  only  scientific  approach  to  this 
problem  is  the  correlation  of  objective  criteria  of  emotional  reaction 
with  those  of  the  introspection.  There  is  at  present  no  criterion  of 
mental  reaction  so  trustworthy  as  the  subject's  own  honest  and  care- 
ful account  of  it.  Sources  of  error  in  the  introspection  of  emotion 
there  are,  indeed,  and  experiments  such  as  those  to  be  described 
throw  light  on  their  nature,  but  the  writers  are  much  out  of  sym- 
pathy with  the  practise  of  going  over  the  head,  or  more  accurately, 
routing  under  the  heels  of  introspection  for  a  psychogenic  explana- 
tion of  any  phenomena  without  the  assurance  that  the  phenomena  in 
question  are  eliminated  from  the  physical  (or  logical)  sources  of 
error  in  the  method. 

The  basis  of  the  mode  of  inquiry  is,  then,  to  present  to  the  sub- 
ject situations  of  greater  or  lesser  emotional  appeal,  to  note  the 
character  of  objective  reaction  thereto,  and  to  compare  it  with  the 
subject's  own  account  of  the  emotional  reaction.  The  free  associa- 
tion test  is,  as  it  happens,  very  much  the  best  means  of  presenting 
such  situations. 

The  objective  criteria  of  emotional  reaction  in  the  association  test 
may  be  considered  as  of  three  sorts:  the  character  of  the  response 
word,  the  reaction  time  of  the  response,  and  the  involuntary  somatic 
reactions. 

Probably  one  of  the  first  things  learned  by  an  experimenter  with 
the  association  test  is  the  wide  variation  in  the  way  in  which  differ- 
ent subjects  "take"  the  experiment.  At  bottom,  this  is  probably 
what  produces  the  difference  between  Sachlicher  Typus  and  Kon- 

26 


THE  REACTION  DEFLECTION  27 

stellationstypus.  There  are  differences  in  temperament  under  which 
some  subjects  react  with  much  more  egocentric  responses  than  others ; 
that  is,  the  responses  are  chosen  much  more  with  reference  to  the 
subject's  special  experience.  Where  this  is  done,  a  Konstellations- 
typus  is  the  general  result.  This  varying  egocentricity  of  the  re- 
sponses is,  however,  not  wholly  a  matter  of  individual  difference,  for 
it  changes  not  a  little  with  the  mood  of  the  subject  at  different  times. 
In  so  far  as  the  responses  give  insight  into  the  nature  of  these  tem- 
peramental differences,  they  are  of  undeniable  value,  but  they  have 
the  disadvantage  of  not  being  very  coercive,  because  there  is  no 
certainty  of  how  far  the  subject  has  observed  or  attempted  to  observe 
the  conditions  of  the  experiment  in  uttering  the  response.  When 
response  words  of  an  intimately  personal  nature  present  themselves, 
pretty  much  every  one  can  "dodge"  and  pretty  much  everyone  does 
do  so,  to  a  greater  or  less  extent.  But  as  dodging  takes  time,  those 
associations  which  involve  suppression  will  tend  to  have  longer  reac- 
tion time  than  those  which  do  not.  The  assertion  of  the  correspond- 
ence of  long  reaction  time  with  heightened  emotional  response  has 
been  very  generally  made,  and  well  supported  on  theoretical  grounds ; 
but  there  is  need  of  more  systematic  correlation  of  this  factor  with 
the  introspective  findings,  before  the  degree  of  its  reliability  can  be 
accurately  estimated. 

Whether  in  the  nature  of  cause,  effect,  or  identity,  the  emotional 
reaction  is  usually  considered  to  be  very  intimately  associated  with 
the  organic  processes.  The  emotional  reaction  is  as  the  introspec- 
tion detects  it ;  the  organic  reaction  we  may  estimate  with  such  degree 
of  accuracy  as  our  objective  methods  permit.  Various  aspects  of  the 
organic  reaction  may  be  considered,  as  the  breathing,  heart-rate, 
blood  pressure  and  the  like.  Judging  from  the  history  of  the  prob- 
lem, it  would  seem  that  the  electrical  reactions  are  those  in  which 
further  study  is  the  most  immediately  desirable. 

Given  the  technique  above  described,  the  problem  becomes  essen- 
tially that  of  observing  the  closeness  of  relationship  between  the 
galvanometric  reaction-deflection,  and  the  introspectively  given  in- 
tensity of  emotional  response.  Since,  in  addition,  the  association 
times  can  be  recorded  (by  a  stop-watch)  without  difficulty,  an  imme- 
diate comparison  is  afforded  of  the  reliability  as  ' '  Komplexindi- 
katoren"  of  the  reaction-deflection  and  the  association  time. 

A  satisfactory  method  of  dealing  with  the  introspective  data  is  of 
course  required.  Since  the  essential  thing  to  determine  is  the  in- 
tensity of  emotional  reaction,  the  object  of  the  experiment  is  best 
served  by  making  the  individual's  task  in  recording  this  datum  as 
simple  and  definite  as  possible.  The  ideal  plan,  of  course,  would  be 


28  ELECTRICAL   PROCESSES   IN    THE   HUMAN   BODY 

to  have  the  subject  arrange  the  different  emotional  reactions  in  the 
order  of  their  intensity,  but  this  is  obviously  impossible.  The  orig- 
inal procedure,  and  that  followed  for  the  most  part,  was  to  assign  the 
reaction  to  one  of  four  groups:  (A)  strongly  emotional,  (B)  rather 
emotional,  (C)  rather  unemotional,  (F)  practically  devoid  of  emo- 
tional reaction.  This  grade  was  determined  by  the  subject  as  soon 
as  possible  after  the  response  was  given,  and  announced  to  the 
operator  when  called  for.  In  some  cases  the  response-words  were 
dispensed  with,  and  the  subject  remained  silent  except  when  asked 
for  the  grade  ;  but  this  diminishes  somewhat  the  efficiency  of  the  pro- 
cedure. It  stands  to  reason  that  the  grade  was  assigned  without  any 
knowledge  of  the  deflection  to  which  it  attached. 

A  short  representative  series  (no  responses  spoken)  is  as  follows: 

Reaction-Deflec- 
Stimulus-word 

peevish 

wrong 

go 

where 

ring 

now 

telltale 

quiet 

widow 


In  matters  of  this  sort,  the  less  the  subject  is  hampered  with  tech- 
nical definitions  of  the  qualities  to  be  graded,  the  more  reliable  his 
gradings  are  likely  to  be.  It  is  much  better  to  let  the  subjects  find 
out  for  themselves  what  they  judge  by  than  to  tell  them  in  the  begin- 
ning to  judge  by  criteria  that  they  can  not  be  expected  to  construe 
in  the  same  way  as  they  are  presented.  With  continued  practise  in 
the  experiment,  it  was  but  natural  that  certain  criteria  should  sepa- 
rate themselves  out  to  the  subjects'  observation.  These  tended  to 
reduce  themselves  more  and  more  to  a  basis  of  somatic  sensation, 
though  the  results  are  not  very  different,  whatever  criteria  are  upper- 
most in  consciousness.  If  it  be  permissible  to  introspect  introspec- 
tion, the  sources  of  error  would,  as  a  matter  of  experience,  operate 
mainly  in  the  direction  of  making  the  grades  too  low.  With  some 
subjects  there  may  be  in  the  first  experiments  a  noticeable  tendency 
to  be  chary  about  assigning  the  highest  grades  at  all,  owing  to  their 
frequent  relation  to  intimate  personal  affairs.  Where  there  is  sup- 
pression, the  grade  is  apt  to  be  underrated.  And  if  the  emotion 
aroused  is  one  that  the  subject  regards  as  of  a  degraded  origin,  it 
may  receive  a  low  grade  independently  of  the  fact  that  the  emotional 
reaction  has  been  quite  pronounced.  Conversely,  ideas  that  might 


Emotional  Grade 

tion  in  mm. 

C 

11 

F 

9 

C  +     the  reaction  was 

11,  then  to  14 

noted  to  "  persist  ): 

B 

20 

B  — 

12 

F2 

8 

F  + 

6 

FI 

9 

C 

7 

B 

20 

THE  REACTION  DEFLECTION  29 

ordinarily  be  associated  with  elevated  emotions  may  be  graded  high, 
though  the  ideas  do  not  now  arouse  such  a  reaction,  but  this  error 
seems  to  reach  serious  proportion  only  in  subjects  quite  unpractised 
in  introspection.  There  seems  to  be  a  real  introspective  awareness 
of  these  sources  of  error,  and  they  can  greatly  distort  a  genuine 
correlation  between  the  functions  observed. 

A  more  refined  method  of  dealing  with  the  introspective  data 
was  evolved  not  only  to  guard  somewhat  against  these  errors,  but 
also  to  obviate  the  external  difficulty  that  the  reaction  deflections 
could  not  be  relied  upon  to  maintain  the  same  order  of  magnitude 
throughout  a  prolonged  experiment.  This  procedure  was  to  segre- 
gate the  associations  into  small  groups,  regularly  of  five,  which  the 
subject  would  then  endeavor  to  arrange  in  order  of  the  intensity  of 
their  emotional  reaction;  or  the  subject  would  grade  the  words  as 
previously,  and  in  case  of  the  same  grade  being  assigned  to  two  of 
the  five  words,  would  decide  which  of  the  two  reactions  had  been 
stronger.  As  an  illustration,  the  following  words  may  be  quoted, 
which  were  given  incidentally,  and  not  as  part  of  a  regular  experi- 
ment. 

Stimulus-word  Emotional  Grade  Reaction-Deflection 
mountain                                         C  +  6 

marry  A  25 

trouble  B  —  2 

hope  B  5 

bicycle  F  1 

(The  correspondence  in  order  is  here  rather  better  than  the 
average;  it  is  in  fact  perfect  except  for  the  displacement  of  moun- 
tain which  may,  however,  owe  much  of  its  deflection  to  having  come 
first  in  the  test.) 

This  is  much  the  more  satisfactory  way  of  making  the  experi- 
ment, when  the  subject's  introspective  ability  is  sufficient  to  per- 
mit it. 

The  observed  relationships  between  the  objective  and  the  intro- 
spective criteria  can  hardly  be  stated  by  any  of  the  more  evolved 
correlation  methods,  since  the  quantitative  relations  of  the  emo- 
tional grades  are  not  sufficiently  definite.  In  the  original  method  of 
recording,  one  is  practically  limited  to  stating  the  central  tendency 
of  the  deflections  that  are  assigned  to  each  group  of  emotional  grades. 

The  greatest  number  of  experiments  is  with  F.L.W.  as  subject, 
and  it  is  perhaps  fair  to  add  that  the  practise  in  introspection  that 
comes  with  special  psychological  training  was  probably  greatest  in 
this  subject. 

Tabulated  as  above,  the  experiments  with  this  subject  resulted 
as  follows : 


30  ELECTRICAL   PROCESSES  IN   THE   HUMAN   BOD7 

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33 


In  the  subjoined  experiments  A.F.  was  subject : 


No.  of 
Expt.  Stimulus- 

Emotional  Grades 

No. 

words 

A 

B 

c 

F 

Remarks 

I. 

25    Av. 

Defl. 

5.5      2.4 

1.4 

1.6 

Body 

resistance. 

Med 

.  Time 

8 

12 

12 

11 

No. 

Cases 

2 

5 

10 

8 

II. 

25     Av. 

Defl. 

13 

6.7 

3.5 

2 

Body 

currents,     electrodes 

in 

Med 

.  Time 

11 

12 

11 

10 

thermostat. 

No. 

Cases 

2 

9 

12 

2 

III. 

10    Av. 

Defl. 

21 

5.2 

8 

Body 

resistance,  shunt  0.1. 

Med 

.  Time 

11 

11 

10 

No. 

Cases 

3 

6 

1 

IV. 

25     Av. 

Defl. 

9 

4 

4 

2 

Body 

currents,     electrodes 

in 

Med 

,  Time 

Not  recorded. 

thermostat. 

No. 

Cases 

2 

9 

8 

6 

V. 

20    Av. 

Defl. 

4 

1.7 

0.7 

1.5 

Body 

resistance,  shunt  .01. 

Med.  Time 

Not  recorded. 

No. 

Cases 

1 

5 

8 

6 

In  the  following  experiment,  the  responses  were  given  without 
the  grades,  which  the  subject  assigned  afterwards  from  memory. 


VI.  91  Av.  Defl. 
Av.  Time 
No.  Cases 


4 
12 
35 


Taking  into  account  the  inaccuracies  of  introspection,  as  well  as 
the  sources  of  error  remaining  in  the  experimental  method,  these 
results  seem  to  show  that  in  central  tendencies  a  fairly  close  rela- 
tionship exists  between  the  intensity  of  the  objective  reaction  and 
the  electrical  disturbances  in  the  tissues  involved.  In  point  of  com- 
parison with  the  association  time,  the  relative  superiority  of  the 
deflections  is  evident. 

What  the  figures  do  not  indicate,  is  the  reliability  of  the  method 
for  individual  cases.  This  is  the  most  important  practical  feature 
of  the  problem,  it  being  of  some  forensic  interest  to  know  with  just 
what  certainty  the  specially  affective  moments  in  an  individual's 
mental  economy  may  be  objectively  determined  and  measured.  For 
the  above  form  of  presentation  this  is  sufficiently  well  indicated  in 
the  mean  variation  of  the  association  times  and  reaction  deflections 
attaching  to  the  different  emotional  grades.  The  following  experi- 
ments, made  some  time  previous  to  the  present  ones,  especially  well 
illustrate  this  relation,  because  both  in  the  naivete  of  the  grading 
and  in  the  intensity  of  the  emotional  reactions  involved,  they  ap- 
proximate more  nearly  than  the  present  tests  to  the  actual  condi- 
tions of  Tatbestandsdiagnostik. 


34  ELECTRICAL   PROCESSES   IN    THE   HUMAN    BODY 

Number 
of  Stim- 
ulus- Emotional  Grade 

words  A          B  C           F                                                           Remarks 

99       Av.  Defl.  50       21  16       15         Body  currents.    Palms  strapped  to  cotton  in  elec- 

M.  V.  10         9  6         7             trode  funnels.     Quoted  from  Wells  and  Cady, 

No.  Cases       2      23  86      38  American  Journal  of  Insanity,  LXV.,  165-166. 

100      Av.  Time  16.5  14.0  11.8  10.9  Observe  that  the  average   and  median  are  prac- 

M.  V.              1.5      1.9     2.0  1.8  tically  the  same;   the  median,  indeed,  tending 

Med.  Time  16.5  15.0  12.0  10.9  to  be  slightly  longer. 

No.  Cases  2  20  37  41 

It  is  easily  seen  that  the  individual  reactions,  outside  those  of 
the  A  grades,  are  subject  to  so  large  a  probable  error  that  neither 
time  nor  deflection  has  much  significance  for  placing  them.  The  de- 
flections which  attach  to  the  A  grades  are  separated  from  the  re- 
mainder by  a  greater  margin  of  probability  than  the  times  are, 
indeed  the  margin  is  here  quite  considerable,  and  it  is  precisely 
these  stronger  reactions  that  it  is  psychodiagnostically  most  im- 
portant to  detect.  Substantially  this  relation  exists  also  in  the  more 
recent  experiments. 

Before  finally  condemning  the  method  for  the  individual  cases, 
except  in  the  strongest  emotional  reactions,  an  examination  may  be 
made  of  its  behavior  in  those  cases  where  the  associations  are  segre- 
gated in  groups  of  five,  and  ordered  in  relative  position.  This  gives 
a  limited  opportunity  for  correlation  by  the  Woodworth  per  cent,  of 
displacement.  Thus  the  example  quoted  on  p.  29  would  show  two 
displacements  out  of  a  possible  10,  20  per  cent. 

Arrangements  of  this  nature  were  available  in  about  a  third  of 
the  experiments  above  quoted,  totalling  36  groups  of  five  reactions, 
23  for  F.L.W.  and  13  for  A.F.  The  correlation  by  the  Woodworth 
per  cent,  of  displacements  is  as  follows  for  the  different  factors 
under  consideration: 

SUMMARY  OF  COBBELATIONS 

The  lower  the  figure,  the  closer  the  correlation;  50  per  cent.  =  0  correlation 

F.L.W.  A.F. 

Defl.  Emot 27  per  cent.  30  per  cent. 

Time  Emot 39  per  cent.  44  per  cent. 

Defl.  Time  38  per  cent.  42  per  cent. 

The  validity  of  these  averages  is  limited  somewhat  by  the  fact 
that  the  differences  in  emotional  reaction  are  greater  in  some  groups 
of  five  than  in  others.  Thus  some  will  contain  only  B  and  C  grades, 
while  others  may  cover  the  complete  range,  A,  B,  C,  F.  Chance 
errors  are  much  more  likely  to  break  down  a  real  correlation  in  the 


THE  REACTION   DEFLECTION  35 

former  case  than  in  the  latter.  As  a  matter  of  fact  the  correlations 
with  the  deflections  are  more  positive,  the  greater  the  range  becomes. 

Of  special  interest  is  the  condition  with  the  A-grades.  In  the 
arrays  considered  this  grade  is  assigned  fourteen  times,  and  in  thir- 
teen cases  it  attaches  to  the  greatest  deflection  in  the  array;  in  the 
fourteenth  it  is  tied  with  a  B-J-.  The  deflections  here  put  in  a  class 
by  themselves  the  reactions  attaining  this  grade,  which,  for  that  mat- 
ter, the  introspection  does  also.  Only  two  of  these  fourteen  A's  have 
the  longest  association  time  in  the  array;  a  third  is  tied  with  a  C. 
Twice  the  time  is  actually  shortest,  and  twice  tied  for  shortest.  The 
greater  reliability  of  the  deflection  is  here  also  evident. 

Unfortunately  it  is  not  so  evident  that  considerably  increased  de- 
flections necessarily  attach  to  an  A  emotional  grade.  There  are  un- 
controlled factors  which  may  occasion  a  considerable  deflection  in 
one  of  the  lower  grades.  Only  when  the  greatest  deflection  in  the 
array  is  half  again  as  much  as  the  next  greatest,  is  it  possible  to  say 
with  comparative  assurance  that  one  is  dealing  here  with  an  emo- 
tional grade  of  A  or  B.  Among  the  sixteen  cases  in  which  such  a 
difference  exists  there  are  two  exceptions,  both  in  F.L.W. 

Special  attention  should  be  called  to  the  fact  that  the  correlation 
of  the  two  objective  criteria — the  deflection  and  the  time — is  but 
slightly  more  positive  than  that  of  the  introspection  and  the  time, 
and  much  less  positive  than  that  of  the  introspection  and  deflection. 
This  militates  considerably  against  any  supposition  that  the  objec- 
tive criteria  are  significantly  influenced  by  any  mental  factors  inde- 
pendent of  the  introspection.  In  so  far  as  these  measures  are 
measures  of  emotional  response,  they  should  be  influenced  together 
by  the  factors  of  the  emotional  response;  and  since  they  are  not  so 
affected  together,  but  their  correlations  with  the  emotional  grades 
are  relatively  independent,  their  relation  to  the  emotional  reaction 
does  not  seem  to  be  influenced  by  extra-conscious  mental  factors  to 
any  important  degree.1 

Previous  mention  has  been  made  of  the  phonograph  as  a  source 
of  emotional  stimuli.  The  advantage  lies  in  the  greater  constancy 

1  When,  as  occasionally  happens,  a  low  emotional  grade  attaches  to  both 
an  increased  deflection  and  a  lengthened  association  time,  this  is  best  inter- 
preted as  the  result  of  calling  up  a  considerable  body  of  rather  vivid  associative 
imagery,  which  lengthens  the  association  time  by  increasing  the  difficulty  of 
choice,  and  at  the  same  time  obscures  the  introspection  of  the  emotional  reac- 
tion. We  can  merely  offer  it  as  a  matter  of  experience  that  less  clear  affects 
are  apt  to  be  considered  less  intense.  One  must  remember  also  the  possibility 
of  suppression  causing  an  underestimation  of  the  emotional  grade.  In  this 
way  the  association  time,  while  of  little  value  in  itself  as  a  measure  of  the 
affect,  may  often  be  useful  in  modifying  the  interpretation  of  the  deflections. 


36  ELECTRICAL   PROCESSES   IN    THE   HUMAN   BODY 

of  stimulus.  It  is  effective  enough  in  the  individuals  of  musical  per- 
ceptions, provided  the  instrument  is  of  a  good  grade  and  carefully 
handled,  and  the  records  properly  selected.  The  writers  found  the 
final  trio  of  Faust  the  most  effective  of  the  records  employed.  Some 
subjects,  unaware  of  the  nature  of  the  phenomenon,  have  observed 
the  deflections  while  listening  to  the  record,  and  discovered  for  them- 
selves the  relation  of  the  movements  of  the  light  to  the  more  stirring 
portions  of  the  record. 

The  above  recounted  experiments  indicate  the  most  that  can  be 
expected  of  the  method  in  its  present  evolution.  The  examination 
of  the  quantitative  relationships  of  the  deflections  in  the  different 
experiments  is  sufficient  to  indicate  how  great  are  the  variations  in 
the  susceptibility  of  the  same  individual  at  different  times.  This 
seems  indeed,  to  be  but  slightly  less  than  that  between  a  number  of 
different  individuals.  There  are  recorded  occasional  experiments 
in  which  the  subject  is  absolutely  refractory,  *'.  e.f  the  electrical  reac- 
tions are  unmeasurably  minute,  or  fail  altogether.  The  greatest 
galvanometric  activity  observed  by  the  writers  in  any  individual  is 
about  ten  times  that  prevailing  in  the  experiments  just  described. 
No  account  has  been  taken  of  any  galvanometric  phenomenon  but 
the  principal  reaction  deflection;  indeed,  the  very  important  ques- 
tion of  the  electrical  reaction  time  has  been  practically  disregarded 
because  the  apparatus  is  not  of  a  type  to  lend  itself  to  precise  de- 
terminations on  this  point.  A  considerable  opportunity  for  advance 
in  the  problem  rests  in  the  improved  instruments  and  methods  that 
are  becoming  available.  For  the  present,  it  would  be  unwise  to 
make  absolute  claims,  but  it  may  be  reasonably  asserted  that  as  an 
objective  criterion  of  emotional  reaction,  the  electrical  reflex  appears 
distinctly  superior  to  any  analogous  procedure  as  yet  developed. 


APPENDIX 

EXAMINATION  OF  PATIENTS 

EXPERIMENTS  were  made  with  four  cases  of  mental  disease,  two  of 
whom  were  cases  of  catatonic  stupor,  one  a  stupor  of  undetermined 
nature,  and  one  of  senile  dementia.  The  senile  case,  although  able  to 
answer  simple  questions,  showed  practically  no  deflections  with  iso- 
potential  electrodes,  when  tested  with  a  variety  of  stimuli.  Grapho- 
phone  records  were  played,  questions  were  asked,  substances  with 
strong  odors  were  held  close  to  the  nose,  and  a  threat  of  a  prick  with 
a  pin  was  made.  Throughout  all  this  series  of  stimuli,  the  deflec- 
tions remained  nearly  constant,  the  ray  of  light  moving  slowly  to 
and  fro,  but  at  no  point  showing  abrupt  changes  such  as  are  noted 
with  ordinary  subjects. 

With  a  second  case,  one  apparently  of  deep  confusion,  with  total 
inaccessibility,  slight  deflections  were  noted,  but  most  of  these  seemed 
associated  with  bodily  activity,  which  it  was  difficult  to  prevent. 
Only  a  few  stimuli  were  given,  and  little  significant  evidence  was  ob- 
tained. 

The  two  cases  of  catatonic  stupor  showed  some  rather  striking 
phenomena.  In  the  first  case,1  the  consciousness  was  fairly  marked, 
and,  although  the  patient  could  not  be  made  to  speak,  he,  neverthe- 
less, seemed  aware  of  his  surroundings  and  inclined  to  resist  the  ef- 
forts to  place  his  fingers  in  the  electrodes.  He  was  finally  induced 
to  comply  long  enough  to  enable  the  putting  of  a  few  questions  and 
the  repetition  of  two  graphophone  records.  Although  the  patient 
showed  no  outward  sign  of  hearing  or  understanding  the  questions, 
a  definite  deflection  followed  each  one  of  them  and  the  magnitude  of 
the  deflections  appeared  significant.  Most  of  them  varied  between 
2  and  13  mm. ;  one,  however,  which  concerned  a  personal  friend,  was 
followed  by  a  deflection  of  49  mm.  Considerable  deflections  oc- 
curred during  the  playing  of  the  graphophone  records,  the  readings 
varying  from  85  mm.  at  the  start  to  108  mm.  at  the  end.  The  sec- 
ond case  of  catatonic  stupor  was  an  admirable  one  for  study.  The 
patient  showed  no  evidence  whatever  of  consciousness,  lying  motion- 
less in  whatever  position  placed.  The  electrode  tubes  were  placed  at 
opposite  sides  of  the  bed  and  the  middle  fingers  of  the  two  hands 

1PThis  patient  had  been  in  the  apparatus  several  times  previously,  with 
similar  results,  in  experiments  from  the  previous  work  of  Wells  and  Cady. 

37 


38  ELECTRICAL   PROCESSES   IN    THE   HUMAN    BODY 

allowed  to  lie  motionless  in  the  fluid.  A  current  from  a  dry  cell  was 
used.  No  stimulus  of  any  sort  produced  any  visible  outward  re- 
sponse. With  the  galvanometer  reduced  to  .01  of  its  sensitivity,  only 
slight  changes  followed  verbal  stimuli,  although  a  deflection  of  12 
mm.  was  produced  by  the  touch  of  a  cold  metal  key  upon  the  fore- 
head. The  galvanometer  was  then  shunted  to  .1  of  its  full  sensitivity 
and  questions  were  addressed  relating  to  events  in  the  patient's 
history,  concerning  which  she  had  talked  during  an  earlier  stage 
of  the  disease.  These  were  interspersed  with  sentences  in  the 
Gothic  language,  which  were,  of  course,  meaningless  to  the  patient. 
Slight  reactions  followed  nearly  all  the  sentences,  whether  English 
or  Gothic.  In  some  cases,  the  reactions  following  questions  of  signifi- 
cance to  the  patient  were  no  greater  than  those  following  Gothic 
sentences,  but  in  certain  instances,  deflections  of  18  mm.  and  in  one 
case,  30  mm.  followed  questions  of  special  significance.  The  touch 
of  a  cold  key  on  the  forehead  caused  a  deflection  of  31  mm. ;  the  en- 
trance of  the  nurse  into  the  room  caused  a  deflection  of  12  mm. ;  the 
shutting  of  a  door  outside  marking  the  approach  of  the  examining 
physician  caused  a  deflection  of  15  mm. 

The  evidence  furnished  by  these  experiments  tended  to  show 
that  the  failure  of  ordinary  response  in  these  cases  of  catatonic 
stupor  resulted  rather  from  inhibition  of  reaction  than  from  fail- 
ure to  apprehend.  They  mark  a  contrast  between  these  conditions 
and  that  of  the  senile  patient,  who  although  able  to  converse  with  a 
slight  degree  of  intelligence,  showed  no  evidence  of  affective  reac- 
tion, and  possibly  also  with  that  of  the  second  named  case,  who 
showed  no  reaction  of  comprehension  to  questions  that  if  understood 
could  scarcely  have  failed  to  be  of  marked  emotional  import. 


LITERATURE   ON  THE   "  PSYCHOGALVANIO  REFLEX" 
AND  ALLIED  PHENOMENA 

TABCIIANOFF.     liber   die  galvanischen  Erscheinungen,   etc.     Pfluger's   Archiv, 
XLVI.,  46-56. 

STICKEB.     liber  Versuche  einer  objectiven  Darstellung  von  Sensibilitatsstb'r- 

ungen.     Wiener  klin.  Rundschau,  XL,  497-501,  514-518. 
SOMMEB.      Zur    Messung    der    motorischen    Begleiterscheinungen    psychischer 

Zustande.    Beitrage  z.  psychiat.  Klinik,  I.,  157-164. 
SOMMEB  u.  FUBSTENAU.    Die  elektrischen  Vorgange  an  der  menschlichen  Haut. 

Klinik  f.  Psych,  u.  Nervds.  Krankh.,  I.,  113. 
VEBAGUTH.     Das   psychogalvanische  Reflexphanomen.     Monatssch.  f.  Psychiat. 

u.  Neurol,  XXL,  387-425. 
PETEBSON  &  JUNG.    Psycho-physical  Investigations  with  the  Galvanometer  and 

Pneumograph  in  Normal  and  Insane  Individuals.     Brain,  XXX.,  153-218. 
JUNG.     On  Psychophysical  Relations  of  the  Associative  Experiment.     Jour,  of 

Abnorm.  Psychol.,  I.,  249-257. 
RICKSHEB  &  JUNG.     Further  Investigations  on  the  Galvanic  Phenomenon  and 

Respiration  in  Normal  and  Insane  Individuals.    Jour,  of  Abnorm.  Psychol., 

II.,  189-217,  and  references. 
BINSWANGEB.     Ueber  das  Verhalten  des  psychogalvanischen  Phanomens  beim 

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